prentice hall physical science chapter 7
TRANSCRIPT
Prentice Hall Physical Science Chapter 7 – Chemical Reactions
7.1 Describing Reactions Chemical Equations
- chemical equations are the written form of a chemical reaction - the original substance that are being changed are called the reactants (usually on the left side) - the new substances that are formed are called the products (usually on the right side)
EX: C + O2 → CO2 C + O2 are the reactants and CO2 is the product
- The law of conservation of mass says that mass is neither created or destroyed in a chemical reaction SO you must have EXACTLY the same number of atoms when a reaction is finished as you did when you started.
- To show this we must balance chemical equations so we have the same number of atoms at the end as we did at the beginning
- We do this by changing the coefficients in front of the chemical formulas. EX: 1) Na + H2O → NaOH + H2 2Na + 2 H2O → 2NaOH + H2 2) HCl + CaCO3 → CaCl2 +CO2 + H2O 2HCl + CaCO3 → CaCl2 +CO2 + H2O 3) Al + Cl2 → AlCl3 2Al + 3Cl2 → 2AlCl3
7.2 Types of Chemical Reactions A. Synthesis Reactions
- when two or more substances react to form a single substance - general equation: A + B → AB - always has two or more reactants but only one product
EX: Mg + O2 → MgO B. Decomposition Reactions
- when one compound breaks down into two or more simpler substances - general equation: AB → A + B - always has one reactant but two or more products
EX: CaCO3 → CaO + CO2 C. Single Replacement Reactions
- when one element (by itself) takes the place of another element that is in a compound - general equation: A + BC → B + AC - always has a single element and a compound as reactant and product
EX: Cu + AgNO3 → Ag + Cu(NO3)2 D. Double Replacement Reactions
- when two different compounds exchange positive ions and form two new compounds - general equation: AB + CD → AC + BD - always has two compounds as reactants and products
EX: Pb(NO3)2 + KI → PbI2 + KNO3 E. Combustion
- when a substance reacts rapidly with oxygen to form carbon dioxide, water, heat, and light EX: CH4 + O2 → CO2 + H2O
The arrow (→)means yield
** Electrons can also be transferred during a chemical reaction. - If an element loses electrons during a chemical reaction it is called oxidation - If an element gains electrons during a chemical reaction it is called reduction
7.3 Energy Changes in Reactions A. Chemical Bonds and Energy
- chemical energy is the energy stored in the chemical bonds of a substance - chemical reactions are when the chemical bonds in the reactants are broken and new bonds
are formed in the reactants B. Exothermic and Endothermic Reactions
exothermic reactions release (give off) energy - the energy of the reactants is greater than the energy of the products
endothermic reactions absorb energy; energy must be added in order for the reaction to “go” - the energy of the products is greater than the energy of the reactants
7.4 Reaction Rate
- reaction rate is how fast a reaction is going - there are several factors that affect reaction rates
A. Temperature - increasing T increases reaction rate because the particles move faster and are more likely to
collide and then react B. Surface Area
- increasing the surface area of the reactants (by making the particles as small as possible) increases the reaction rate because there are more surfaces for collisions and the more collisions, the faster the reaction happens
C. Stirring - stirring increases reaction rates because stirring increases the exposure of the reactants to
each other D. Concentration
- concentration is how much reactant you have - increasing the concentration of the reactants increases the reaction rate because there are
more reactants to collide and therefore react E. Catalysts
- a catalyst is a substance that speeds up a reaction without being used up by the reaction because it can allow the reaction to happen at a lower temperature
So to the left is a molecule of water…and you already KNOW you write the formula for water H2O, right? Because there is one oxygen and two hydrogen. So how would you write the formula for propane by looking at the model below? Well you just count how many C’s and how many H’s there are. ________
Name: ___________________ Chemical Reactions – If you have the ability, take pictures of each page and upload into Google Classroom
7.1 Describing Reactions
________________ _______________
- chemical equations are the written form of a ________________ _______________
- the original substance that are being changed are called the __________________ (usually on the left side)
- the new substances that are formed are called the__________________ (usually on the right side)
EX: C + O2 → CO2
C + O2 are the reactants and CO2 is the product
- The law of conservation of _________ says that mass is neither _______________ or ________________
in a chemical reaction SO you must have __________________ the same number of atoms when a
reaction is_________________ as you did when you ___________________.
- To show this we must __________________ chemical equations so we have the same number of
__________________ at the end as we did at the beginning
- We do this by changing the __________________ in front of the chemical formulas.
EX: 1) Na + H2O → NaOH + H2
2Na + 2 H2O → 2NaOH + H2
2) HCl + CaCO3 → CaCl2 +CO2 + H2O
2HCl + CaCO3 → CaCl2 +CO2 + H2O
3) Al + Cl2 → AlCl3
2Al + 3Cl2 → 2AlCl3
7.2 Types of Chemical Reactions
A. ___________________ Reactions
- when ___________ or more substances ____________ to form a __________ substance
- general equation: ____ + ____ → ____
- always has ________ or more reactants but only ________ product
EX: Mg + O2 → MgO
B. ___________________ Reactions
- when _________ compound breaks down into _________ or more ___________ substances
- general equation: ____ → ____ + ____
- always has ______ reactant but ________ or more products
EX: CaCO3 → CaO + CO2
The arrow (→)means ___________
C. _____________ ___________________ Reactions
- when one element (by itself) takes the ________ of another element that is in a compound
- general equation: ____ + ____ → ____ + ____
- always has a ____________ element and a ___________ as reactant and product
EX: Cu + AgNO3 → Ag + Cu(NO3)2
D. _____________ ___________________ Reactions
- when ______ different compounds exchange _______ ions and form two new compounds
- general equation: ____ + ____ → ____ + ____
- always has _______ compounds as reactants and products
EX: Pb(NO3)2 + KI → PbI2 + KNO3
E. ___________________
- when a substance reacts rapidly with _______ to form carbon dioxide, water, heat, and light
EX: CH4 + O2 → CO2 + H2O
** Electrons can also be _______________ during a chemical reaction.
- If an element _______ electrons during a chemical reaction it is called _______________
- If an element _______ electrons during a chemical reaction it is called _______________
7.3 Energy Changes in Reactions
A. Chemical Bonds and Energy
- chemical ______________is the energy stored in the chemical _____________ of a substance
- chemical reactions are when the chemical bonds in the reactants are _______________ and
new bonds are _______________in the reactants
B. Exothermic and Endothermic Reactions
_______________ reactions _______________ (give off) energy
o the energy of the _______________ is greater than the energy of the products
_______________ reactions _______________ energy; energy must be added in order for the
reaction to “__________”
o the energy of the _______________is greater than the energy of the reactants
7.4 Reaction Rate
- _______________ _______________ is how _______________a reaction is going
- there are several factors that affect reaction rates
A. _____________________
- increasing T increases reaction rate because the particles move faster and are more likely to
collide and then react
B. _____________ ________
- increasing the surface area of the reactants (by making the particles as small as possible)
increases the reaction rate because there are more surfaces for collisions and the more
collisions, the faster the reaction happens
C. _____________________
- stirring increases reaction rates because stirring increases the ___________ of the reactants
to each other
D. _____________________
- ___________________ is how much reactant you have
- increasing the concentration of the reactants increases the reaction_______ because there
are more reactants to collide and therefore react
E. _____________________
- a catalyst is a substance that ________up a reaction without being ________ up by the
reaction because it can allow the reaction to happen at a ___________ temperature
So to the left is a molecule of water…and you already KNOW you write the
formula for water H2O, right? Because there is one oxygen and two
hydrogen. So how would you write the formula for propane by looking at
the model below? Well you just count how many C’s and how many H’s
there are.
________
(write answer)
Test # Type (Prefix, Root or
Suffix) Root or Affix Meaning Example
8 root feder alliance federation
8 root fen to strike fend
8 root fer to bear suffer
8 root fess speak confess
8 root fidel trust confidence
8 root fin end finale
8 root flagr blaze flagrant
8 root flex bend flexible
8 root flor flower florist
8 root fluct wave fluctuation
8 prefix fore in front of forefront
8 root form shape form
8 root fort strong fortuitous
8 root fortun fate fortune
8 root frag break or shatter fragmentation
8 root frig cool frigid
8 root fug flee or run fugitive
8 root fum smoke fume
8 root found to pour or melt foundry
8 suffix fy make or do glorify
Name _________________________________________ Date ____________________ Block ________ Test # ________ (Fill this in!!)
Type (Prefix, Root
or Suffix) root or affix meaning examples
Understanding Chemical Equations Name: Period: Date:
INSTRUCTIONS: List each individual element in the reactants and the products. Use the coefficient and the subscripts to calculate the number of atoms of each element.
(NOTE: When a subscript is affected by a coefficient you must multiply the subscript by the coefficient (i.e. 2H2 means (2x2=4 Hydrogen atoms). If everything equals, the
equation is balanced. The Law of the Conservation of Mass says that every atom that "goes into" a chemical reaction must "come out of" the chemical reaction .
Reactant - A substance or molecule that "goes into" a chemical reaction (left of yields sign "->" ).
Product - A substance that "comes out of" a chemical reaction (right of yields sign "->" ).
Coefficient - A number that is placed in front of a chemical symbol or formula (marked with ) that affects all of
the combined elements to the right.
Subscript - A number written below and to the right of a chemical symbol (marked with ) that affects only the
element to which it is connected.
Chemical Equation Name the REACTANTS Name the PRODUCTS Balanced?
(Everything
Equals)
# Atoms of Each
Element
Total Atoms
Yields # Atoms of Each
Element
Total Atoms
1
2H2 + O2 → 2H2O
H - 4
O - 2
6
→
H - 4
O - 2
6
Y / N
2
N2 + 2H2 → NH3
→
Y / N
3
HgO → Hg + O2
→
Y / N
4
2N2 + O2 → 2N2O
→
Y / N
5
Na + H2O → NaOH + H2
→
Y / N
Chemical Equation Name the REACTANTS Name the PRODUCTS Balanced?
(Everything
Equals)
# Atoms of Each
Element
Total Atoms
Yields # Atoms of Each
Element
Total Atoms
6
4Si2H3 + 11O2 → 8SiO2 + 6H2O
→
Y / N
7
2Fe + O2 → 2FeO
→
Y / N
8
5P4 + 2O2 → P2O5
→
Y / N
9
Na2CO3 + 2HCl → 2NaCl + H2O + CO2
→
Y / N
10
Fe2O3 + H2 → Fe + H2O
→
Y / N
11
6CO2 + 6H2O → C6H12O6 + 6O2
→
Y / N
12
Fe2(SO4)3 + 3KOH → 3K2SO4 + 2Fe(OH)3
→
Y / N
8th Grade Science - Mr. Allison
Mole Conversions Worksheet First know that:
• Mass is measured in grams. “Find the mass of” means find the number of grams.
• Volume is measured in liters. “What is the volume of” means find the number of liters.
• Particles are atoms, molecules or formula units. It can be any of these three!
Converting between to moles from moles
grams and moles: use molar mass
(add up masses from periodic table)
1 mol
XX.X g
XX.X g
1 mol
liters and moles of a gas at STP
1 mol
22.4 L
22.4 L
1 mol
particles and moles (particles are
atoms, molecules or formula units)
1 mol
6.02 x 1023 particles
6.02 x 1023 particles
1 mol
Mole conversion steps:
1. Identify what you are converting from and what you are converting to.
2. Determine if the conversion is one or two steps:
a. If either the from or the to is moles, then the conversion requires only a single step.
b. If neither the from nor the to is moles, then two steps are required. In the first step you will convert
to moles and in the second step, from moles.
3. Set up the problem:
1. Write the given value (the from). This is a number AND a unit AND the element or compound
symbol or formula. You can’t forget the unit! Put all of this over a 1 to hold your place!
2. Write a multiplication sign (x)
3. Draw a line _________________
4. Whatever your given unit was to start with, it has to be on the bottom of the line that you drew in step
#3. This will have a standard number to go with it. If it is mol, it will be a 1. If it is atoms, molecules
or formula units it will be Avagadro’s number 6.02 x 1023. If it is grams, then it will be a number you
had to calculate. This is so the unit will cancel out.
5. Whatever unit you are trying to solve for must be written on the TOP of the line you drew in step
#3. This will also have a standard number to go with it.
6. Each step must include AND the element or compound symbol or formula
7. Multiply by the conversion factor (see table above). What you are converting to goes in the
numerator and what you are converting from goes in the denominator. You multiply the numbers
across the top and multiply the numbers across the bottom and then divide the top by the bottom! IT
is NOT cross multiply!!!
8. Any like terms that are diagonal can be cancelled out, just like in math class!
Solve the problem. Show how units cancel and use the correct number of significant digits.
One step example
What is the mass of 1.673 moles of copper?
From: moles To: grams
1.673 mol Cu x 63.546 g Cu = 106.3 g Cu
1 1 mol Cu
Two step example
What is the volume of 9.36 g of methane gas (CH4) at
STP?
From: grams To: liters
9.36 g CH4 x 1 mol CH4 x 22.4 L = 13.1 L CH4
1 16 g CH4 1 mol CH4
(Page is intentionally left blank)
Mole Conversions Worksheet Name: ____________________ Date: _____________________
Directions: Show ALL of your work. Make sure to include units!!!!
Mole-Mass Conversions (use the molar mass for your conversions)
1. How many moles are in 28 grams of CO2 ? (molar mass 44.01g)
_______________________ X ___________________ = 1
2. What is the mass of 5 moles of Fe2O3 ? (molar mass 159.7g)
_______________________ X ___________________ = 1
3. Find the number of moles of argon in 452 g of argon. (molar mass – 39.95g)
_______________________ X ___________________ = 1
4. How many grams are in 3.45 moles of CO2? (molar mass 44.01g)
_______________________ X ___________________ = 1
Mole-Particle Conversions (use Avogadro’s number for your conversions)
1. How many moles of magnesium are in 3.01 x 1022 atoms of magnesium?
_______________________ X ___________________ = 1
2. How many molecules are there in 4.00 moles of glucose, C6H12O6?
_______________________ X ___________________ = 1
3. How many moles are 1.20 x 1025 formula units of calcium iodide?
_______________________ X ___________________ = 1
4. How many formula units are in 12.5 moles of calcium phosphate?
_______________________ X ___________________ = 1
Gram to Particle Conversions (two step conversions using molar mass and Avogadro’s number)
1. How many oxygen molecules are in 3.36 g of oxygen (O2) [molar mass – 32g]?
_______________________ X ___________________ X ___________________ = 1
2. Find the mass in grams of 2.00 x 1023 molecules of F2. (molar mass 38g)
_____________________ X ___________________ X ___________________ = 1
3. Determine the number of molecules of 14 g of nitrogen dioxide (NO2). (molar mass 46.01 g)
_____________________ X ___________________ X ___________________ = 1
4. Find the mass, in grams, of 1.00 x 1023 molecules of N2 (molar mass – 28.02g)
_____________________ X ___________________ X ___________________ = 1
5. Aspartame is an artificial sweetener that is 160 times sweeter than sucrose (table sugar) when dissolved in water. It is marketed by G.D. Searle as Nutra Sweet. The molecular formula of aspartame is C
14H
18N
2O
5 .
a) Calculate the molar mass of aspartame.
Element Atoms Atomic mass Total C x = H x = N x = O x = +
g b) How many moles are in 10.5 g of aspartame? _______________________ X ___________________ = 1 c) How many molecules are in 10.5 g of aspartame? _______________________ X ___________________ = 1
Test # Type (Prefix, Root or
Suffix) Root or Affix Meaning Example
9 root gam marriage polygamy
9 root gastr stomach gastric
9 root gen race, family, kind, birth generation, degenerate, genetics
9 root geo earth geography, geomagnetism, geophysics
9 root ger, gest bear, carry congest, gestation
9 root glotto, glot, glott tongue, or “speech language” glottologist
9 root gno, kno to know knowledge
9 root grad, gred, gress walk, step, take steps, gradient
9 root gram, graph something written or drawn, a record cardiogram, telegram
9 root grand great grandiose
9 root grat pleasure, thankful, goodwill, joy congratulate, gratify
9 root grav, griev heavy, weighty gravity
9 root greg flock, herd congregate
9 root gust, gast taste, stomach/digestive gustatory, disgusting, gastric
9 prefix gymno, gymn naked, uncovered, unclad gymnasium
9 root gyro ring, whirl gyroscope, autogyro
9 root hab to have, hold, dwell habitat
9 root helio, heli sun heliograph, heliocentric
9 prefix hemi half hemisphere
9 root hemo blood hemoglobin, hemophilia
Name _________________________________________ Date ____________________ Block ________ Test # ________ (Fill this in!!)
Type (Prefix, Root
or Suffix) root or affix meaning examples
Name __________________________________ Date ________________
Reactions and Conversion Review
1. Reactants _________________________________________________________________
2. Products __________________________________________________________________
3. Law of Conservation of mass __________________________________________________
____________________________________________________________________________
You will have to be able to balance an equation
4. What are the missing coefficients for the skeleton equation below?
Al2(SO4)3+ KOH→ Al(OH)3+ K2SO4
A) 1,3,2,3
B) 2,12,4,6
C) 4,6,2,3
D) 1,6,2,3
E) 2,3,1,1
5. What are the missing coefficients for the skeleton equation below?
Cr + Fe(NO3)2 → Fe + Cr(NO3)3
A) 4,6,6,2
B) 2,3,2,3
C) 2,3,3,2
D) 1,3,3,1
E) 2,3,1,2
Write
Element
Symbol
These two columns must equal
each other to be balanced!
Elements # of Atoms on
Reactant Side
# of Atoms on
Product Side
Write
Element
Symbol
These two columns must equal
each other to be balanced!
Elements # of Atoms on
Reactant Side
# of Atoms on
Product Side
There will be easy matching on the definitions to the 5 reactions…..they are on your notes and
board! You must know the example equation (like is on #9) for each (except combustion)
6. Synthesis reaction
7. Decomposition Reaction
8. Single replacement reaction
9. Double Replacement Reaction AB + CD → AD + CB
10. Combustion Reaction
11. What does the → mean? ______________
You will have to work conversion problems – mass to mole, mole to mass, atoms to mols, mols
to atoms.
LEARN Avogadro’s number! 6.02 x 1023
You will have to calculate molar mass.
11. What is the molar mass of
(NH4)2SO4? We have already done this!
a) 114.09g/mole
b) 118.34g/mole
c) 128.06g/mole
d) 132.13g/mole
12. How many moles of NO2 are present in 114.95g? The molar mass of NO2 is 46.01 g/mole.
a) 0.4003mol b) 1.000mol c) 2.498mol d) 114.95mol
______________ X ______________ = ______________
Element Atoms Atomic mass Total
N x =
H x =
S x =
O x = +
g/mol
13. How many grams of CCl4 are needed to have 5.000 mol? The molar mass of CCl4 is 153.81g/mol.
a) 5.000g b) 30.76g c) 769.0g d) 796.05g
______________ X ______________ = ______________
14. How many atoms are present in 3.00 mol of Ca(OH)2? They use Avogadro’s number!!
__________________ X __________________ = __________________
15. 829 grams of NaOH to molecules –Molar mass of NaOH (40g)
__________________ X __________________ X __________________ = __________________
16. 7.78 X 1023 atoms of Ca to grams (40 g)
__________________ X __________________ X __________________ = __________________
17. Endothermic reaction
18. Exothermic reaction
19. Which of these is a balanced chemical equation for the synthesis of NaBr from Na and Br2?
a. Na + Br2 → NaBr b. 2Na + Br → NaBr c. Na + Br2 → NaBr d. 2Na + Br2 → 2NaBr
20. Which of the following is a balanced chemical equation for the synthesis of H2O from H2 and O2? a. H2 + O2 → 2H2O c. 2H2 + O2 → H2O b. H2 + O2 → H2O d. 2H2 + O2 → 2H2O
21. Methane, CH4, burns in the presence of oxygen gas to form (or yield) water and carbon dioxide. What is the correct balanced chemical equation for this reaction? a. CH4 + O → H2O + CO2 c. CH4 + O2 → H2O + CO2 b. CH4 + 4O → 2H2O + CO2 d. CH4 + 2O2 → 2H2O + CO2
22. What is the molar mass of carbon dioxide, CaCO3? You will need this mass for the next question. Use your
periodic table. It may need be exact, but it will be close.
Element Atoms Atomic mass
Total
x =
x =
x = +
g/mol
23. What is the molar mass of magnesium chloride, MgCl2?
Element Atoms Atomic mass
Total
x =
x = +
g/mol
24. What is the molar mass of magnesium chloride, CO2?
Element Atoms Atomic mass
Total
x =
x = +
g/mol
Chapter 10 Nuclear Chemistry
10.1 Radioactivity
* Discovered by Henri Becquerel in 1896.
* He hypothesized that uranium salts produced X-rays when exposed to sunlight. To test it he exposed
some to sunlight and wrapped it in photographic paper. They left an image on the paper.
* Several days of bad weather caused him to be unable to retest his hypothesis. The salts remained
wrapped in photographic paper on his desk. When he developed it, he found an image the same
as the one before.
* This caused him to determine uranium gave off rays that had never been observed before.
A. Nuclear Decay
- radioactivity is the process in which an unstable atomic nucleus emits charged particles and energy
- any atom containing an unstable nucleus is a radioactive isotope or radioisotope.
- radioisotope: radioactive isotope - any atom that has an unstable nucleus.
- radioisotopes, like uranium-238 and carbon-14, spontaneously change into other isotopes over time
- nuclear decay is when atoms of one element can change into atoms of a completely different element
- Isotopes are named using the element name followed by the mass number
- The symbol for isotopes includes the element symbol, the mass number and the atomic number as
follows:
This is called elemental Notation
B. Types of Nuclear Radiation
- nuclear radiation is the charged particles and energy that are emitted from the nuclei of radioisotopes
Radiation Type Symbol Charge Mass (amu) Common Source
Alpha particle ,
He4
2 2+ 4 Radium-226
Beta particle
e0
1− 1- __1__ 1836
Carbon-14
Gamma ray
0 0 Cobalt-60
U238
92Uranium-238
C14
6
Carbon-14
Po210
94
Polonium-210
Mass # on top
Atomic # on bottom
1. Alpha Decay – a positively charged particle made of two protons and two neutrons (the same as
a helium nucleus)
- an alpha particle is 42He ()
- 2 protons and 2 neutrons
- Positively charged
- Same as He nucleus
- in alpha decay the resulting atom has two fewer protons and two fewer neutrons than it
did to start with
- it is the least penetrating type of nuclear radiation;
- it travels only centimeters in the air
- they can be stopped by paper or clothing
- ex: 23892U → 234
90Th + 42He
2. Beta Decay – an electron emitted from an unstable nucleus
- a beta particle is 0-1e ()
- 1 electron
- Negatively charged
- Produced by a neutron that decomposes into a proton and an electron
- during beta decay, a neutron in the nucleus in a radioisotope decompose into a proton and an
electron; the proton is left behind in the nucleus and the electron is emitted
- in beta decay the resulting atom has one more proton and one less neutron than it started with
- More penetrating than particles
- beta particles can pass through paper,
- it can be stopped by a thin sheet of metal
- ex: 23490Th → 234
91Pa + 0-1e
3. Gamma Decay – a ray of energy emitted from an unstable nucleus
- a gamma ray is just a penetrating ray of energy ()
- it has no mass and no charge
- like x-rays and light, it has only a very short wavelength
- they travel at the speed of light
- Most penetrating (can go thru) forms of the three types listed
- Often accompanies alpha or beta decay
- several centimeters of lead or several meters of concrete are required to stop it
Writing and Balancing Nuclear Reactions
◼ Similar to chemical equations, but isotope symbols are used.
reactants→ products
◼ In a balanced nuclear equation:
Mass # on the left = sum of mass #s on the right
Atomic # on the left = sum of atomic #s on the right
◼ You will need to use your PERIODIC TABLES!
++→
+→
− ePaTh
HeThU
0
1
234
91
234
90
4
2
234
90
238
92
C. Effects of Nuclear Radiation
- background radiation is the radiation that occurs naturally in the environment
Sources:
◼ Radioisotopes in air, water, rocks & living things
◼ Cosmic radiation
Generally, these are all usually at safe levels
- when nuclear radiation exceeds background radiation it can damage body cells and tissues
- Nuclear radiation can ionize atoms. At levels significantly above background, this can damage DNA
and proteins
- alpha particles cause skin damage similar to a sunburn and are not really dangerous unless
inhaled or eaten
- Radon – 222 is a potentially dangerous source of alpha particles
- beta particles are more penetrating and can do more damage
- gamma rays can penetrate even more and expose organs to damage
D. Detecting Nuclear Radiation
- Geiger counters
use a gas filled tube to measure ionizing radiation
- Gas produces an electric current when exposed to ionizing radiation
- Film Badges
Photographic film wrapped in paper
Film is exposed with exposure to radiation like photographic film is “exposed” with exposure to
visible light
10.2 Rates of Nuclear Decay
* Scientists use rates of nuclear decay to estimate how old materials are
A. Half-life – the time required for one-half of a sample of a radioisotope to decay (turn into a different
element)
- after one half-life, half of the atoms in the original sample have turned into something new and
half remain unchanged
- after two half-lives, half of what remained has decayed leaving ¼ as atoms from the original
sample
Different radioisotopes have different half-lives
To determine how many half-lives have elapsed for a sample, divide the total time of decay by
the half-life
Known decay rates are used in radioactive dating
- nuclear decay rates are constant; they do not vary with conditions; nothing can change them
- ex: You have 1 g of iridium – 182 which has a half-life of 15 minutes. It decays to form osmium-182.
After 45 minutes, how much iridium-182 remains?
Half-lives elapsed = total time of decay/half-life
= 45 min/15 min
= 3 half-lives
So, the amount of iridium has been reduced by half three times
½ * ½ * 1/2 = 1/8
1/8 * 1 g = 0.125 g
B. Radioactive Dating
- scientists use the known half-lives and the amount of original radioisotopes remaining in
something to determine an objects age
- ex: You have a sample that was originally iridium-182. Three fourths of it has
already decayed into osmium-182. Since only ¼ of the sample is still iridium-182, you
can calculate the age to be two half-lives or 30 minutes.
- Radiocarbon dating
- All living and formerly living things contain the radioisotope carbon-14 which they
get from taking in carbon from plants.
- Once an organism dies, it cannot take in more carbon-14, so the carbon-14 decays
and is not replaced.
- the object’s age can be determined by comparing the object’s carbon-14 levels to
carbon-14 levels in the atmosphere
- the half life of carbon-14 is 5730 years
- this way of dating is not completely accurate because the levels of carbon-14 in the
atmosphere change
- it can be used to date anything les than 50,000 years old
- the older the material, the less carbon-14 it has
10.3 Artificial Transmutation
A. Nuclear Reactions in the Laboratory
- transmutation is changing atoms of one element into atoms of another element
- Alchemists have attempted this for hundreds of years (but not through nuclear chemistry)
- scientists can perform transmutations by bombarding atomic nuclei with high energy particles
such as protons, neutrons, or alpha particles
- First artificial transmutation: Ernest Rutherford (1919) turning nitrogen into oxygen-17. Where
have we heard this name before?
B. Transuranium Elements
- they are elements with atomic numbers greater than 92
- they are all radioactive
- scientists can make them with artificial transmutation
- first one made was Neptunium-239
- americium-241 is made to be used in smoke detectors
- plutonium-238 is used for electrical energy generation in space probes
C. Particle Accelerators
- sometimes artificial transmutation won’t happen unless the bombarding particles are moving at
extremely high speeds
- in a particle accelerator the bombarding particles are accelerated to very high speeds
- scientists have made 3000 different isotopes
- it has also allowed more than 200 different subatomic particles to be detected
- these are the particles that make up protons and neutrons
- one of these is called a quark; it makes up protons and neutrons
10.4 Fission and Fusion
* The nucleus of an atom contains an enormous amount of energy
* During transmutation mass, from the nucleus, is converted into energy
A. Nuclear Forces
◼ The strong nuclear force attracts protons and neutrons.
Stronger than electric forces over short distances
Decreases with distance (like gravity)
◼ Electric repulsions push protons apart.
◼ When a nucleus is large enough, the electric forces can overcome the strong nuclear forces.
- Nuclei are unstable at this point.
- Any atom with 83 or more protons is unstable – and, therefore, radioactive.
B. Fission
- fission is the splitting of one nucleus into two or more smaller parts
- Lise Meitner, Fritz Strassman and Otto Hahn’s experiments (1939) first demonstrated nuclear
fission.
- A small amount of the original mass is converted into a lot of energy
Fission
- E = mc2; m = the mass “lost” during transmutation and c = the speed of light (3.0 * 108 m/s)
- during fission one reaction leads to a series of others causing a chain reaction
- in a chain reaction, neutrons released during the splitting of an initial nucleus trigger more
nuclear fissions
- critical mass is the smallest possible mass of a fissionable material that can sustain a chain
reaction
- nuclear power plants use controlled fission reactions of uranium-235 to generate heat and
electricity
- generates nuclear waste
- Fission can result in a chain reaction. Neutrons released from the first reaction can trigger another
reaction, and so on – similar to a rumor spreading.
◼ For a chain reaction to happen, each split nucleus must produce at least one neutron with enough energy
to split another nucleus
This only happens when a specific mass of fissionable material is available – called the critical
mass.
Controlled chain reactions are used to generate electricity in nuclear power plants.
Uncontrolled chain reactions are used in nuclear weapons
C. Fusion - the process in which the nuclei of two atoms combine to form a larger nucleus
- a small amount of the mass from the original two elements is converted to energy
- The sun and other stars are powered by fusion of H into He
- Requires extremely HIGH temperatures
- What state is matter in at such high temperatures? PLASMA
- plasma is the state of matter in which atoms have been stripped of their electrons so it is
essentially a gas with two kinds of particles, nuclei and electrons
-21H + 31H → 42He + 10n + energy
- it is clean and scientists want to build a fusion reactor but there are two problems
1. it requires VERY high temperatures
2. they must contain the plasma
Name ___________________________ Chapter 10 Nuclear Chemistry
10.1 Radioactivity
* Discovered by Henri Becquerel in ________.
* He hypothesized that uranium salts produced _________ when exposed to __________. To test it he
exposed some to sunlight and wrapped it in photographic ___________. They left an image on the paper.
* Several days of bad weather caused him to be unable to retest his hypothesis. The __________
remained wrapped in photographic __________ on his desk. When he developed it, he found an
image the same as the one before.
* This caused him to determine _______________ gave off rays that had never been __________ before.
A. Nuclear Decay
- _________________ is the process in which an unstable atomic _________emits __________
_____________ and ______________
- any atom containing an _________ nucleus is a ____________________ isotope or radioisotope.
- ______________________________: radioactive isotope - any atom that has an unstable nucleus.
- radioisotopes, like uranium-_____and carbon-____, spontaneously ____________ into other isotopes
over time
- _____________ _____________ is when atoms of one element can _______ into atoms of a completely
different element
- ____________are named using the element ____________ followed by the mass ____________
- The symbol for isotopes includes the element ____________, the _______ ___________ and the
___________ number as follows:
- this is called _________________ ________________
B. Types of Nuclear Radiation
- nuclear __________is the charged particles and energy that are emitted from the _______ of radioisotopes
Radiation Type Symbol Charge Mass (amu) Common Source
Alpha particle
Beta particle
Gamma ray
Alpha Decay He4
2
1. _________ _________ – a positively charged particle made of two ____________ and two ___________
(the same as a helium nucleus)
- an alpha particle is______ ()
2 ____________ and 2 ______________
______________ charged
Same as the _____________ nucleus
- in alpha decay the resulting atom has two fewer _______ and two fewer _______ than it did to start with
- it is the _________ penetrating type of nuclear radiation;
- it travels only centimeters in the ______
- they can be stopped by __________ or __________
An example: 23892U → 234
90Th + 42He
Beta Decay e0
1−
2. Beta Decay – an __________emitted from an unstable nucleus
- a beta particle ()
- 1 _____________
- ______________ charged
- Produced by a neutron that ____________ into a __________ and an ____________
- during beta decay, a neutron in the nucleus in a radioisotope_____________ into a __________
and an __________;
the proton is left behind in the nucleus and the electron is ____________ (given off)
- in beta decay the resulting atom has one _______ proton & one _____neutron than it started with
More ________________ than particles
- beta particles can ________ through paper
- it can be stopped by a thin sheet of ____________
An example
- ex: 23490Th → 234
91Pa + 0-1e
Gamma Decay – a ray of _____________ emitted from an unstable nucleus
Gamma Ray - a gamma ray is just a penetrating ray of ____________ ()
- it has no ______and no _______
- like X-rays and light, it has only a very _______ wavelength
- they travel at the speed of ___________
Most ________________ (can go through) form of the three types listed
- often accompanies _____________or ____________decay
- Several centimeters of ___________ or several meters of __________ are required to stop it
Writing and Balancing Nuclear Reactions
◼ Similar to chemical ________________, but isotope ______________are used.
reactants→ products
◼ In a balanced nuclear equation:
________ # on the left = sum of ____________ #s on the right
________ # on the left = sum of ___________ #s on the right
◼ How to write a balanced nuclear equation for the alpha decay of polonium.
Step 1: Define ___________ and ____________. Use letters to represent the unknown values.
isotope.product of symbol chemical X and ,# mass A ,# atomic Let Z ===
Po210
84 He4
2 XA
Z Step 2: Write and solve ____________ to find ______________ atomic and mass #s.
2064210
4210
=−=
+=
A
A
82284
284
=−=
+=
Z
Z
Step 3: Look up the element__________ on the periodic table using the atomic ________.
Atomic # 82 = ____ (__________)
Step 4: Write the balanced nuclear equation and double-check your solution.
PbHePo 206
82
4
2
210
84 +→
C. Effects of Nuclear Radiation
- ____________ radiation is the radiation that occurs naturally in the environment
Sources:
◼ Radioisotopes in ______, ________, ________& living things
◼ ________ radiation
Generally, these are all usually at _________ levels
when nuclear radiation ________ background radiation it can damage body ______ and ___________
- Nuclear radiation can ________ atoms. At levels significantly above background, this can damage
____________ and ________
- alpha particles cause skin damage similar to a ______________ and are not really dangerous unless
____________ or ____________
- _____________ – 222 is a potentially dangerous source of ______________ particles
- __________ particles are more _________________ and can do more damage
- ___________ ___________ can penetrate even ______ and expose ________ to damage
++→
+→
− ePaTh
HeThU
0
1
234
91
234
90
4
2
234
90
238
92
+
D. Detecting Nuclear Radiation
- ______________ ________________
use a gas filled tube to measure ionizing ___________________
- ________ produces an electric current when exposed to ionizing radiation
- ______________ ________________
Photographic _______ wrapped in paper
_______ is exposed with exposure to radiation like photographic __________ is “exposed” with
exposure to visible ____________
10.2 Rates of Nuclear Decay
Scientists use ________ of nuclear decay to estimate how old materials are
________ ______ – the time required for ________-_________ of a sample of a radioisotope to decay
(turn into a different element)
- after _______half-life, half of the atoms in the original sample have turned into something
_________ and half remain __________________
- after_______ half-lives, half of what remained has ____________ leaving ____as atoms from the
original sample
Different radioisotopes have different half-lives
To determine how many half-lives have elapsed for a sample, ________ the total time of decay
by the half-life
______________ decay rates are used in radioactive dating
- nuclear decay rates are_________; they do ______ vary with conditions; ___________ can change them
ex: You have 1 g of iridium – 182 which has a half-life of 15 minutes. It decays to form osmium-182. After
45 minutes, how much iridium-182 remains?
Half-lives elapsed = total time of decay/half-life
= 45 min/15 min
= 3 half-lives
So, the amount of iridium has been reduced by half three times
½ * ½ * 1/2 = 1/8
1/8 * 1 g = 0.125 g
B. Radioactive Dating
- scientists use the ____________ half-lives and the amount of original radioisotopes remaining in
something to ______________ an objects ______
- ex: You have a sample that was originally iridium-182. Three fourths of it has already decayed into
osmium-182. Since only ¼ of the sample is still iridium-182, you can calculate the age to be two
half-lives or 30 minutes.
Radiocarbon dating
All ___________and ____________living things contain the radioisotope carbon-14 which they get from taking in
_____________ from plants.
- Once an organism ______, it cannot take in more ________-14, so the carbon-14 decays and is not replaced.
- the object’s _______ can be determined by comparing the _________ carbon-14 levels to carbon-14
levels in the ______________
- the _______-__________ of carbon-14 is _________ years
- this way of dating is not completely ____________ because the levels of carbon-14 in the
atmosphere change
- it can be used to date anything less than _____________ years old
- the older the material, the _______ carbon-14 it has
10.3 Artificial Transmutation
A. Nuclear Reactions in the Laboratory
- _________________ is conversion atoms of one element into atoms of another element
- ______________have attempted this for hundreds of years (but not through nuclear chemistry)
- scientists can perform transmutations by bombarding atomic _________ with high energy particles
such as ___________, ___________, or ___________ particles
- First artificial transmutation: _________ _____________ (1919) turned nitrogen into oxygen-17 Where
have we heard his name before?
B. Transuranium Elements
- they are elements with atomic numbers greater than _____
- they are all___________________
- scientists can make them with ________________transmutation
- first one made was ____________-239
- _____________________-241 is made to be used in ___________ _____________
- _____________________-238 is used for electrical energy generation in _________ __________
C. Particle Accelerators
- sometimes artificial transmutation won’t happen unless the bombarding particles are moving at
extremely ________speeds
- in a particle accelerator the bombarding particles are accelerated to very high _______
- scientists have made __________ different isotopes
- it has also allowed more than _____ different subatomic particles to be detected
- these are the particles that make up _________ and _____________
- one of these is called a _________; it makes up protons and neutrons
10.4 Fission and Fusion
* The nucleus of an atom contains an enormous amount of __________
* During transmutation, _____ from the nucleus, is converted into energy
A. Nuclear Forces
◼ The strong ____________ force attracts protons and neutrons.
Stronger than electric forces over _____________ _____________
Decreases with distance (like ___________ does)
◼ Electric repulsions push ___________apart.
◼ When a nucleus is large enough, the ___________ forces can overcome the strong_________ forces.
- Nuclei are ____________ at this point.
- Any atom with _____ or more protons is unstable – and, therefore, ______________.
B. Fission
- _______is the splitting of one nucleus into two or more smaller parts
- Lise Meitner, Fritz Strassman and Otto Hahn’s experiments (______) first demonstrated
_______________ fission.
- A small amount of the original _______ is converted into a lot of _____________
Fission
- E = mc2; m = the mass “_______” during transmutation and c = the speed of light (3.0 * 108 m/s)
- during fission one reaction leads to a ________ of others causing a ________ reaction
- in a chain reaction, ___________released during the splitting of an initial ____________ trigger
more ____________ _____________
- _______________ mass is the smallest possible mass of a fissionable material that can sustain a
__________________ _________________
- nuclear ________ plants use controlled fission reactions of uranium-_____ to generate __________ and
_________________
- generates nuclear _____________
- __________can result in a chain reaction. Neutrons released from the first reaction can trigger
another reaction, and so on – similar to a rumor spreading.
◼ For a chain reaction to happen, each _______ nucleus must produce at least _____ neutron with enough
energy to split another nucleus
This only happens when a specific mass of fissionable material is available – called the
____________ ____________
_______________chain reactions are used to generate electricity in nuclear power plants.
_______________ chain reactions are used in nuclear weapons
______________- the process in which the nuclei of two atoms combine to form a larger nucleus
- The ______ and other _________ are powered by fusion of H into He
- Requires extremely________ temperatures
- What state is matter in at such high temperatures? ___________ (this was the last state of matter we didn’t really
talk about!)
- ___________ is the state of matter in which atoms have been ___________ of their electrons so it is
essentially a gas with two kinds of particles, nuclei and electrons
-21H + 31H → 42He + 10n + energy
it is ____________ and scientists want to build a fusion reactor but there are two problems
1. it requires __________ high temperatures
2. they must contain the_____________
Name __________________ Date ____________ Block _____
What Is Your Estimated Annual Radiation Dose?
(the average radiation dose per person in the United States is about 360 millirems per year. Use the following sheet to
estimate your annual exposure to background radiation)
Source Your Average Annual
Dose (mrem)
Natural Radiation
Radon 200
Uranium and other elements from the ground:
What region of the US do you live in?
• Coastal regions, add 16 mrem
• Colorado Plateau, add 63 mrem
• Elsewhere in United States, add 30 mrem
Carbon-14 and Potassium-40 (this is internal radiation in your body from food and water 40
Houses made of stone, adobe brick, or concrete building? If yes, add 7 mrem
Cosmic radiation at sea level (depends on elevation)
What is the elevation (in feet) of your town?
• up to 1000, add 26 mrem
• 1,000 - 2,000, add 31 mrem
• 2,000 - 3,000, add 35 mrem
• 3,000 - 4,000, add 41 mrem
• 4,000 - 5,000, add 47 mrem
• 5,000 - 6,000, add 29 mrem
Artificial Radiation
X-Rays
• Dental x-rays, add 1 mrem
• Arm or leg, add 1 mrem
• Chest x-rays, add 6 mrem
• Skull/neck, add 20 mrem
• Upper GI, add 245 mrem
• Pelvis hip, add 65 mrem
Nuclear Medicine
• CAT Scan (head and body, add 110 mrem
• Nuclear Medicine (e. g., thyroid scan) add 14 mrem
Do you watch TV? If yes, add 1 or 2 mrem
Do you use a computer? If yes, add .1 mrem
Air Travel (1 mrem per 2-hour flight)
TOTAL YEARLY DOSE (in mrem) Add all of the number above and put them in the blank on the
next page where it says to put total
Name __________________ Date ____________ Block _____
Calculate all of your percentages. Remember… it is part divided by the
whole times 100.
So first…..total all your numbers—write it here ____________
Do each part divided by your total times 100 and round it to a whole
number. Write percentages below.
Radon ________
Uranium and other ground elements (ours is 30) ________
Carbon 14 and Potassium 40 ________
House ________
Cosmic radiation (ours is 26) ________
X-rays (everyone’s can be different) ________
Nuclear Medicine ________
Watching TV (2) ________
Working with a computer ________
Flying in airplane (.5 for each hour flown) ________
Now….do percentages equal 100? Put them in the pie and color and
label. If they don’t double check your numbers until you get 100%. You
made an error somewhere if it doesn’t
Name __________________ Date ____________ Block _____
Alpha Decay
Alpha particle
Alpha particles are helium nuclei released from an unstable nucleus. It is classified as ionizing radiation. The alpha particle is positively charged containing two protons, two neutrons and no electrons. The alpha particle will be able to pick up two electrons from nearby atoms. The symbol for the alpha particle is:
Alpha particles are emitted from the nucleus atom at 10 percent the speed of light. The penetrating power of the alpha particle is very low since it will not be able to penetrate a thin sheet of paper. Because of this low penetrating power, the alpha particle will do severe damage to the cells if taken into the body. One method of entering the body is by inhalation.
Nuclear equation: Below is an example of a nuclear reaction involving the emission of an alpha particle.
In this reaction U-238 is changed into Th-234 by emission of an alpha particle. Notice that both the atomic mass of the element and the atomic number decrease. During alpha decay, the atomic mass of the element undergoing the change decreases by four and the atomic number by two.
Alpha decay sample problem
Radium-226 (Ra) decays by alpha emission. Write a balanced equation for this nuclear decay:
Solution
From the periodic table, the atomic number for radium is 88. Write an alpha particle as 42He. Decay means "to give off":
therefore, radium is on the reactant side of the equation, and the alpha particle plus some other element must be among the products:
For the atomic number in the reactant to equal the atomic numbers in the products, the atomic number of the new element (?) must be 86.
88 = 2 +x
x = 86
Apply the same method to the mass number, and hence the mass number for the new element (?) is 222.
226 = 4 + x
x = 222
Refer again to the periodic table and look up the symbol of the element with an atomic number of 86. The symbol Rn for radon. Therefore, the equation for this nuclear reaction is
Name_________________________________
Alpha Decay Problems
Directions: On this sheet of paper answer the following problems dealing with alpha decay.
1. Curium-240 (Cm) decays by alpha emission
2. Uranium-232 (U) decays by alpha emission
3. Americium-243 (Am) decays by alpha emission
4. Plutonium-239 (Pu) decays by alpha emission
5. Polonium-210 (Po) decays by alpha emission
6. Lawrencium – 256 (Lr) decays by alpha emission
7. Proctactinium – 231 – (Pa) decays by alpha emission
8. Gold – 185 – (Au) decays by alpha emission
9. Francium – 211 (Fr) decays by alpha emission
10. Polonium 208 (Po) decays by alpha emission
11. Uranium 233 (U) decays by alpha emission
12. Platinum 175 (Pt) decays by alpha emission
13. Tungsten 184 (W) decays by alpha emission
Beta Decay
Beta particles are identical to electrons. Since electrons do not exist in the nucleus of an atom they come from a neutron by the following reaction:
A beta particle is written by use of the following symbol:
The -1 represents the atomic number of the electron. Since the electron has a very small mass compared to the proton, the atomic mass of the electron is zero. Beta particles are emitted from the nucleus at 0.9 times the velocity of light. Beta particles penetrating power is greater than that of the alpha particle. Aluminum foil approximately 1 cm in thickness will stop the beta particle. Beta particles are also harmful if ingested into the body. Beta particles have an ionizing effect on gases.
Nuclear Equation:
The emission of a beta particle from the nucleus of an atom is represented by the following reaction.
Beta Decay Sample Problem
Bromine-82 decays by beta emission. Write a balanced equation for this nuclear reaction.
Solution: Using the Periodic Table to determine the atomic number of bromine, and knowing that the symbol for a beta particle is written:
You can write an incomplete equation by looking up the atomic number on the periodic table.
The atomic number for the new element is 36:
35 = -1 + x
x = 36
The mass number for the new element is 82 since the proton and neutron have equal mass. The mass number does not change. When refering to the Periodic Table, Krypton (Kr) has the atomic number of 36. Therefore the nuclear equation is:
Name_________________________________ Date ________________
Beta Decay Problems
On a this sheet of paper, write a balanced equation for each of the following nuclear reactions.
1. Krypton-87 (Kr) decays by beta emission
2. Zinc-71 decays by beta emission
3. Silicon-32 decays by beta emission
4. Cobalt-60 decays by beta emission
5. Magnesium-27 decays by beta emission
6. Sodium 24 decays by beta emission
7. Americium 247 decays by beta emission
8. Technetium 99 decays by beta emission
9. Bromine 82 decays by beta emission
10. Gold 201 decays by beta emission
11. Strontium 90 decays by beta emission
12. Carbon 14 decays by beta emission
13. Cobalt 60 decays by beta emission
Positrons
Some nuclei emit positrons. Positrons have the same mass as an electron but are positively charged. The positrons last a very short time. The symbol for a positron is:
No positrons exist in the nucleus of an atom, however the emission of the positron can result from the conversion of a proton to a neutron.
With in about 10-9 s, the positron combines with an electron and is converted to gamma rays. Positrons are similar to beta particles in velocity and ionizing effect, however they have very low penetrating power.
Positron Decay Example
Oxygen 15 decays by positron emission. Write a balance equation for this nuclear reaction.
Solution:
Using the Periodic Table to determine the atomic number of oxygen, and knowing that the symbol for a positron is written:
You can write the incomplete equation by looking up the atomic number on the periodic table
The atomic number for the new element is 7, and the mass number is 15.
8 = 1 +x
x = 7
From the Periodic Table, the new element is nitrogen (N), and the equation for this nuclear reaction is:
Name_________________________________
Positron Problems
On a separate sheet of paper, please solve these problems dealing with positron decay.
1. Rubidium-81 decays by emitting a positron.
2. Germanium-66 decays by positron emission.
3. Praseodymium-140 (Pr) decays by positron emission.
4. Neon-18 decays by positron emission.
5. Copper-59 decays by positron emission.
6. Fluorine 18 decays by positron emission
7. Silicon 26 decays by positron emission
8. Magnesium 23 decays by positron emission
9. Calcium 41 decays by positron emission
10. Manganese 50 decays by positron emission
11. Phosphorus 30 decays by positron emission
12. Boron 8 decays by positron emission
13. Zinc 61 decays by positron emission
Electron Capture
Sometimes an electron from an inner energy level may be captured by the nucleus of an atom. When the electron is capture it converts a proton into a neutron. The atom becomes electronically excited. An electron from the valance shell drops down to the empty orbital emitting x-rays. Nuclei with an atomic number greater that 83 cannot achieve stability by electron, positron, or electron capture. You write an electron the following way.
Electron Capture Example
Krypton 40 undergoes electron capture. Write a balanced equation for this nuclear reaction.
Using the Periodic Table to determine the atomic number of Krypton, and knowing that the symbol for electron capture is written:
You can write an incomplete equation by looking up the atomic number of Krypton on the periodic table
?
The atomic number for the new element is 18, and the mass number is 40.
19 + -1= x
x = 18
From the Periodic Table, the new element is argon (Ar), and the equation for this nuclear reaction is:
Name ________________________________ Date _____________ The following all undergo electron capture. Write the complete nuclear equation.
1. Silver 106 (Ag) undergoes electron capture
2. Tin 116 (Sn) undergoes electron capture
3. Platinum 190 (Pt) undergoes electron capture
4. Iodine 123 (I) undergoes electron capture
5. Argon 37 (Ar) undergoes electron capture
6. Krypton 89 (Kr) undergoes electron capture
7. Chromium 51 (Cr) undergoes electron capture
8. Strontium 80 (Sr) undergoes electron capture
9. Thulium 168 (Tm) undergoes electron capture
10. Einsteinium 247 (Es) undergoes electron capture
11. Barium 128 (Ba) undergoes electron capture
12. Arsenic 73 (As) undergoes electron capture
13. Ruthenium 97 (Ru) undergoes electron capture
Name _________________________ Fill this out using the pages of notes and examples
In order to work any of the equations on the various radiation worksheets, you have to be able to write a nuclide. Nuclides are specific types of atoms or nuclei. Every nuclide has a chemical element symbol (X) as we as an atomic number (Z) (which is the number of protons in the nucleus) and a mass number (A) (which is the total number of protons and neutrons in the nucleus.
Type of Nuclear Reaction
What do you take out or add in?
Atomic Number does what? Goes up or down by how many?
Mass Number does what? Goes up or down by how many?
Alpha Decay
↓ by 2 ↓ by 4
Beta Decay or Emission
Positron Decay or Emission
Electron is on the right hand side of the
equation
Electron
Capture
Electron is on the left hand side of the
equation
Gamma Decay
0 0
Test # Type (Prefix, Root or
Suffix) Root or Affix Meaning Example
10 root her, hes stick, cling adhere, cohesive, cohesion
10 root herb plants herbaceous, herbicide
10 prefix hetero, heter different, another, unlike heterosexual, heterogeneous
10 root hippo, hipp horse hippopotamus
10 root holo whole holistic, wholesome
10 prefix homo, hom same, alike homogeneous, homosexual
10 root hosp guest, host hospital
10 root host enemy, stranger hostile
10 root hydro, hydra water hydrate, hydroplane
10 prefix hyper more, above, excessive hyperactive, hypodermic needle
10 root hypno sleep hypnosis
10 prefix hypo to little hypoactive, hypodermic
10 suffix iatry, iatrics healing, science of healing pediatrics, podiatry, geriatric
10 suffix ic like, having the nature of tragic, caloric, pandemic
10 root icono, icon image, likeness, sacred icon
10 root icthy fish ichthyology, ichthyosaur
10 root idem the same identify
10 root ideo idea ideology, ideal
10 root idios one’s own idiosyncrasy, idiom
10 root ign, igni, ignis fire, burn ignite, ignition
Name _________________________________________ Date ____________________ Block ________ Test # ________ (Fill this in!!)
Type (Prefix, Root
or Suffix) root or affix meaning examples
Name _______________________________________Chapter 10 Nuclear Decay Review Sheet Use power point notes first.
1. Who discovered Radioactivity in 1896?
2. What is radioactivity?
3. A radioisotope is any atom that has an unstable ___________________.
4. When atoms of one element can change into atoms of a completely different element, it is known as what?
5. ________________________ substances have unstable nuclei because they have either too many or too few neutrons
6. Are x-rays a type of nuclear radiation? ________________
7. What is the unit we use to measure the amount of radiation a person is exposed to? _________
8. A person exposure to radiation can be affected by their __________, where they ______, and if they smoke.
Using the isotope below..
9. What is the atomic number of this element?
10. What is the mass number of this element?
11. What element is it?
12. This is the type of radiation that we are continually exposed from the Sun, soil, rocks
and plants. ____________________ ____________________
13. What holds protons and neutrons together in a nucleus?
14. Define half-life
15. If one half-life, half of the atoms in the original sample have turned into something new and half remain unchanged…
a. The how much of the original atoms will be left after two half-lives?
b. How much is left after three half-lives?
C14
6
16. What is the half live of carbon-14? (on powerpoint – memorize)
17. Older the material will have (more, less) carbon-14 than newer material.
18. What will change the rate of nuclear decay? NOTHING
19. Element Sodium-26 has a half-life of 4 years. How many years would it take for a 28 mg sample to decay to 7 mg?
Match the following and either Alpha decay, Beta decay, or Gamma decay. Check the type of decay in the column. This information is on your powerpoint
Alpha Beta Gamma Positron
20. Stopped by a thin sheet of metal
21. a ray of energy emitted from an unstable nucleus
22. Charge of 0
23. Least penetrating type of nuclear radiation
24. Charge of 2+
25. has no mass and no charge
26. an electron emitted from an unstable nucleus
27. It takes several centimeters of lead or several meters of concrete required to stop it (penetrates the furthest though any matter)
28. Produced by a neutron that decomposes into a proton and an electron
29. Charge of -1
30. Travel only centimeters in air
31. Most penetrating form of the three types discussed
32.
33. Can be stopped by a sheet of paper or clothing
34. Same as He nucleus
35. Like X-rays and light, only very short wavelength
36. They travel at the speed of light
37. -
38. +
39. atom has two fewer protons and two fewer neutrons than it did to start with
40. In alpha decay, two protons and two neutrons are (gained, lost) in the nucleus.
41. During Beta decay, a nucleus loses an ____________________
42. When a nucleus undergoes gamma decay, the atomic number of the element stays the same!
There is NO change in the atomic nucleus, just an energy release. (two separate questions)
He4
2
e0
1
e0
1
43. The alpha decay of radon- 198
44. The beta decay of uranium-237
45. Positron emission from silicon-26
46. Sodium-22 undergoes electron capture
47.
48.
49. Beta decay of Potassium 42
50. Alpha decay of Plutonium 239
51. Beta decay of Cobalt 60
52. Alpha decay of Radium 226
53. Positron decay of Boron 8
54. Positron Decay of Neon 18
55. Electron Capture of Argon 37
56. What is the biggest disadvantage of using nuclear decay as a power source?
57. Short-live isotopes called radioactive tracers are used to monitor water flow through
crops.
58. (Fission, Fusion) is when nuclei combine so nuclei get (smaller, bigger) and (lighter, heavier).
59. (Fission, Fusion) is when nuclei split so nuclei get (smaller, bigger) and (lighter, heavier).
60. The _______________ ___________ refers to the minimum amount of substance that can undergo a fission reaction and can also sustain a chain reaction.
Test # Type (Prefix, Root or
Suffix) Root or Affix Meaning Example
11 Root imag likeness image
11 prefix in, im, ir not incredible, immoral, inhospitable
11 prefix infra beneath, below infrastructure
11 root init to begin, enter upon initiate
11 root integ untouched, whole integrate, integer, integral
11 prefix inter between, among international, interfaith, internet,
intercellular
11 prefix intra within, inside intranet
11 suffix ism the act, state, or theory of criticism, optimism, capitalism
11 prefix iso equal isometric, isosceles, isotonic
11 suffix ist one who does… conformist, copyist, cyclist
11 suffix itis inflammation, burning sensation encephalitis, hepatitis
11 suffix ive of, belonging to productive
11 suffix ize, ise forms verbs from nouns and adjectives formalize, jeopardize, legalize,
modernize,
11 root ject, jac to throw eject, inject, interject, project
11 root jug yoke (bind together) juggle, conjugal
11 root junct join, unite, yoke junction
11 root jur, just, jud law jury, justice, jurisdiction
11 root juven young juvenile
11 prefix kil, kilo thousand kilowatt
11 root kine movement, muscular activity kinetic activity, kinesthetics
Name _________________________________________ Date ____________________ Block ________ Test # ________ (Fill this in!!)
Type (Prefix, Root
or Suffix) root or affix meaning examples
MOTION
• How do you know something is moving? o Depends on your frame of reference. o To describe motion accurately and completely, a frame of reference is necessary o The frame of reference is the location from which motion is observed. o Most common: the earth.
How fast are you moving?
• Relative motion is movement in relation to a frame of reference.
• You must choose a meaningful frame of reference to allow you to describe motion in a clear and relevant matter.
Measuring distance
• Distance: the length of a path between two points.
• When an object moves in a straight line, the distance is the length of the line connecting the object’s
starting point and its ending point.
• Distance tells you how far an object has moved. It does not depend on direction.
• Distance is a scalar quantity. o Magnitude (how far) o No direction required
• Choose a unit that is best suited for the motion being described.
• SI unit for measuring distance is meters.
• Examples: meters, kilometers, centimeters
Measuring displacement
• To describe an objects position relative to a given point, you need to know how far away and in what direction the object is from that point.
• Displacement is independent of the path taken by the object.
• Displacement is the direction from the starting point and the length of a straight line from the starting point to the ending point.
Combining Displacements
• Displacement is an example of a vector.
• A vector is a quantity that has magnitude and direction.
• The magnitude can be size, length or amount.
• Arrows on a graph or map are used to represent vectors.
• The length of the arrows shows the magnitude of the vector.
• Vector addition is the combining of vector magnitudes and directions.
Adding vectors
• When the vectors are along the same plane they are added arithmetically.
• Many different methods for adding vectors that do not lie in the same plane.
Name ____________________________________ Date ____________________ Block __________
A physical science student runs in the path shown below. How far did he run? What was his final displacement?
The diagram shows the path of a cross country skier. Point A is the starting point. According to the diagram,
what distance did she travel while skiing? What was her final displacement?
Measuring Displacement Not along a straight line
• When 2 or more displacements have different directions, the total displacement can be found by graphing a
resultant vector
• Resultant Vector – Straight line going directly from starting point to ending point
What is the difference between distance and displacement?
What units would you use to express distance? Displacement?
Can you think of a scenario where an object moves a certain distance,
but has a displacement of zero?
What is SPEED?
• The ratio of distance an object moves to the amount of time it takes to move that distance.
• How fast or slow an object is traveling.
• Is speed a vector or a scalar quantity? It is scalar! Average Speed (V)
• Defined as the total distance / total time. Or V = d/t
• Average speed is useful because it lets you know how long a trip will take
Example Problem Calculating Average Speed
❖ While traveling on vacation, you measure the times and distances traveled. You travel 35 kilometers in 0.4
hour, followed by 53 kilometers in 0.6 hour. What is your average speed?
Total distance (d) = 35 km + 53 km = 88km
Total time (t) = 0.4h + 0.6h = 1 h
V = 88km
1hr
Instantaneous speed
• Not as useful in physical science. Much more difficult to calculate.
• Defined as the speed at a given moment in time. • A speedometer gives you instantaneous speed
Graphing motion
• Distance-time graphs.
• The slope of a line on a distance-time graph is the speed.
• Using the graph on the slide… what speed is the student walking down the hallway?
Velocity
• The speed and direction in which an object is moving is called velocity.
• Velocity is a description of both speed and direction of motion.
• Velocity is a vector.
• A change in velocity can be the result of a change in speed, a change in direction, or both.
Speed vs velocity
• Velocity is speed in a given direction.
• MUST have a direction.
• Considered a vector quantity Combining Velocities
• This is done when the motion of an object involves more than one velocity
What is acceleration?
• Acceleration is the rate at which velocity changes.
• Acceleration can be described as changes in speed, changes in direction or changes in both.
• “Speeding up or slowing down”
• “changing direction”
• Science definition: the rate of change of velocity
• Can be both negative and positive
• Acceleration is a VECTOR quantity.
• The distance-time graph for acceleration is always a curve.
What is the formula for acceleration?
• Acceleration = final velocity – original velocity A = ∆ V (vf - vi) Time T
• Or the change in velocity ( v) / time (∆t)
• Label : m/sec/sec or m/sec2
Example problems:
• A roller coaster’s velocity at the top of a hill is 10 m/sec. Two seconds later it reaches the bottom of the hill with a velocity of 26 m/sec. What is the acceleration of the roller coaster? A = (26-10)
2
• A roller coaster is moving 25 m/sec at the bottom of a hill. Three seconds later it reaches the top of the hill and is traveling at a speed of 10 m/sec. What was the roller coaster’s acceleration?
• Can you have negative acceleration? YES. The negative sign tells us the direction of the acceleration, usually means deceleration.
Free Fall
• The movement of an object toward Earth solely because of gravity
• All objects fall at the same rate
• 9.8 m/sec2
Graphing acceleration
• Distance-time graph for constant acceleration always a curve.
• Velocity-time graph for constant acceleration always a straight line
Changes in Direction
❖ Acceleration isn’t always the result of changes in speed. You can accelerate even if your speed is constant. You
experience this type of acceleration if you ride a bicycle around a curve.
Changes in Speed and Direction
❖ Sometimes motion is characterized by changes in both speed and direction at the same time. You experience
this type of motion if you ride on a roller coaster like the one on the next slide. It stats our slowly as the cars
travel up the steep incline and then they reach the top and plummet to the ground and whip around a curve.
You are thrown backwards, forwards and sideways as your velocity increases, decreases and changes direction.
Your acceleration is constantly changing.
Constant Acceleration
❖ Constant acceleration is a steady change in velocity. The velocity of the object changes by the same about
each second. An example is an airplane’s acceleration on a portion of its take off.
Calculating Acceleration
❖ Acceleration is the rate at which velocity changes.
❖ You calculate acceleration for straight-line motion by dividing the change in velocity by the total time.
❖ Acceleration = change in velocity = (vf – vi)
Total Time t
In the formula above, velocity is in the numerator and time is in the denominator.
❖ If the velocity increases, the numerator is positive and thus the acceleration is also positive. For example if you are
coasting downhill on a bicycle, your velocity increases and your acceleration is positive. If the velocity decreases, then
the numerator is negative and the acceleration is also negative. For example, if you continue coasting after you reach
the bottom of the hill, your velocity decreases and your acceleration is negative.
❖ Remember that acceleration and velocity are both vector quantities. If an object moving at constant speed changes
its direction of travel, there is still acceleration. In other words, the acceleration can occur even if the speed is
constant. Think about a car moving at a constant speed as it rounds a curve. Because its direction is changing, the
car is accelerating.
❖ To determine a change in velocity, subtract one velocity vector from another. If the motion is in a straight line,
however, the velocity can be treated as speed. You can then find acceleration from the change in speed divided by the
time.
Acceleration
A flowerpot falls off a second-story windowsill. The flowerpot starts from rest and hits the sidewalk 1.5 s later
with a velocity of 14.7 m/s. Find the average acceleration of the flowerpot.
1. List the given and the unknown values.
Given: time, t = 1.5 s
initial velocity, vi = 0 m/s
final velocity, vf = 14.7 m/s down
Unknown: acceleration, a = ? (m/s2 and direction)
2. Write the equation for acceleration.
acceleration = change in velocity = (vf – vi)
Total Time t
3. Insert the known values into the equation, and solve.
a = 14.7m/s – 0m/s
1.5s
a = 9.8 m/s2
Graphing Accelerated Motion
The slope of a straight line on a speed vs. time graph is equal to the acceleration.
Speed-Time Graphs
〉 How can a graph be used to find acceleration? For example, consider a
downhill skier who is moving in a straight line. After traveling down the hill
for 1 second, the skier’s speed is 4 meters per second. In the next second, the
speed increases by an additional 4 meters per second, so the skier’s
acceleration is 4 m/s2.
〉 Constant acceleration is represented on a speed-time graph by a straight line.
The graph is an example of a linear graph, in which the displayed data form
straight-line parts. The slop of the line is the acceleration.
❖ Constant negative acceleration decreases speed. The speed time graph to the
right shows the motion of a bicycle slowing to a stop. The horizontal line segment
represents constant speed. The line segment sloping downward represents the
bicycle slowing down. The change in speed is negative, so the slope of the line is
negative.
Graphing Accelerated Motion
❖ Acceleration can also be seen on a distance vs. time graph.
❖ The distance vs. time graph is not a straight line when the velocity is
not constant.
❖ This curved line indicates that the object is under acceleration.
Graphing Skills
Graphing Acceleration
A bus traveling on a straight road at 20 m/s uniformly slows to a stop over 20 s. The bus remains stopped for 20
s, then accelerates at a rate of 1.5 m/s2 for 10 s, and then continues at a constant speed. Graph speed vs. time for
60 s. What is the bus’s final speed?
1. Determine the x-axis and the y-axis of your graph.
The x-axis will indicate time, t, measured in s. The y-axis will indicate speed, v, measured in m/s.
2. Starting from the origin, graph each section of the motion.
A. Draw and connect the first two points:
t = 0 s, v = 20 m/s
t = 20 s, v = 0 m/s
B. Draw a horizontal line from t = 20 s to t = 40 s at v = 0 m/s.
C. Starting at t = 40 s and v = 0 m/s, draw a line with a slope of 1.5 m/s2.
D. Draw a horizontal line from t = 50 s to t = 60 s at v = 15 m/s.
3. Read the graph to find the final speed.
At time t = 60 s, the speed is 15 m/s.
Instantaneous Acceleration
• Acceleration is rarely constant, and motion is rarely in a straight line. Instantaneous acceleration is how fast a velocity is changing at a specific instant
• Acceleration involves a change in velocity or direction or both, so the vector of the acceleration can point in any direction.
Forces and Motion What is Force?
• A push or pull that acts on an object • Can cause a resting object to move • Can accelerate a moving object
– By changing its speed or direction
How is force measured? • Spring scale
– Stretch of the spring depends on the mass of the object acting on it • Unit of Force
– Newton (N) – 1 kg to accelerate 1 m/s2
21
s
mkgN
•=
How is force represented? • Use arrows
– Direction – Strength
• Length represents strength or magnitude
The scale with more apples, greater mass, has a longer arrow. The arrow is pointed downward due to mass is below the balance pulling downwards.
Combining Forces • Forces in the same direction are added together • Force in the opposite direction are subtracted • Net Force
– Overall force acting on an object Balanced vs. Unbalanced Forces
• Balanced – Combine to produce a net force of zero – No change in the object’s motion
• Unbalanced – Net force equals the size of the larger force minus the size of the smaller force – Net force does not equal zero – Causes an object to accelerate
Representing Forces Adding Forces
Subtracting Forces
Equal and opposite forces
So in the case above, you’d add 100 N + 90 N and get 190 N to the right. You KNOW it’s being pulled 180 N to the left.
The notes says forces in the opposite direction are subtracted. So you subtract 190 N – 180 N and get a net force of 10
N and the box would move to the right. It would mean its unbalanced because the net force doesn’t equal zero.
Because these two have equal forces acting on it, the net force is zero.
Friction
• Force that opposes the motion of objects that touch as they move past each other • Acts at the surface where objects are in contact • 4 types of friction
4 Types of Friction • Static friction
– Force that acts on objects that are not moving – Always acts in the direction opposite to that of the applied force
Sliding friction – Force that opposes the direction of motion of an object as it slides over a surface
Rolling friction
– Change in shape at the point of rolling contact
Fluid friction – Opposes the motion of an object through fluid – Increases the speed of the object moving through the fluid – Fluids (gas and liquids)
Gravity (pic right) • Force that acts between two masses
– An attractive force that pulls objects together • Earth’s gravity - Acts downwards towards the center of the earth
Gravity and Falling Objects (left) - Gravity causes objects to accelerate downward - Air resistance (fluid friction) acts in the direction opposite to the motion and reduces acceleration - Terminal velocity is the constant velocity of a falling object when force of resistance equals gravity
Projectile Motion • Motion of a falling object after given an initial forward velocity • Causes a curved path
Newton’s 1st Law of Motion • Law of inertia
• Inertia is the tendency of an object to resist change in its motion • State of an object does not change as long as the net force acting on it is zero •An object at rest stays at rest, an object in motion stays in motion at the same direction and speed (until something acts on it)
• •Newton’s 2nd Law of Motion
• The acceleration of an object is equal to the net force acting on it divided by the objects mass – Mass
• Measure of inertia of an object and depends on the amount of matter the object contains
• The acceleration of an object is always in the same direction as the net force • Net forces in the opposite direction of object’s motion
– Force produces deceleration and reduces speed – Ex. Seat belts
• Units for Acceleration are equivalent – N/kg=m/s2
An example of Newton’s Second Law is when we use crash-test dummies. Dummies are used in simulated car crashes to study what might happen to passengers in a real crash. They are fitted
with a range of measuring devices that tract the motion of the dummies throughout the crash. By analyzing the data,
scientists learn how injuries occur and how they can be prevented. What forces act on the crash-test dummy to slow
its forward movement?
Weight and Mass
• Weight & Mass are Different • Weight
– The force of gravity acting on an object – Product of the mass and acceleration due to gravity – Unit is Newtons (N)
• Mass is a measure of the inertia of an object; weight is a measure of the force of gravity acting
on an object
Newton’s 2nd Law of Motion – Example and Practice Problems
1. A boy pushes forward a cart of groceries with a total mass of 40.0 kg. What is the acceleration of the cart if the net force on the cart is 60.0 N?
A = F/m A = 60.0 N/40.0 kg A = 1.50 m/s2
2.What is the upward acceleration of a helicopter with a mass of 5000 kg if a force of 10,000 N acts
on it in an upward direction? A = F/m A = 10000 N/5000 Kkg A = 2 m/s2
3.An automobile with a mass of 1200 kg accelerates at a rate of 3.0 m/s2 in the forward direction. What is the net force acting on the automobile? (Hint: Solve the acceleration formula for force.)
4.A 25-N force accelerates a boy in a wheelchair at 0.5 m/s2 What is the mass of the boy and the wheelchair? (Hint: Solve Newton's second law for mass.)
Newton’s 3rd Law of Motion & Momentum • 3rd Law – when an object exerts a force on a second object, that object exerts an equal and
opposite force on the first object • Momentum
– Product of an object’s mass and its velocity – Objects momentum at rest is zero – Unit kg m/s
Newton’s 3rd Law of Motion & Momentum The two forces are called action and reaction forces. • According to Newton’s 3rd Law, there must be an equal and opposite reaction force. • Not all action and reaction forces produce motion. • Only when equal and opposite forces act on the same object do they result in a net force of zero.
Law of Conservation of Momentum
• If no net force acts on a system, then the total momentum of the system does not change • In a closed system, loss of momentum of one object equals the gain in momentum of another
object
Universal Forces
• Four different forces exist throughout the universe. – Electromagnetic – Strong Nuclear – Weak Nuclear – Gravitational – All the universal forces act over a distance between particles of matter, which means the
particles do not need to be in contact with one another.
Universal Forces Electromagnetic Forces
– Electromagnetic force is associated with charged particles – Electric forces and magnetic forces are the only forces that can both attract and repel
Electric forces – Electric forces act between Charged objects or particles such as electrons or protons – Objects with like charges repel while objects with opposite charges attract
Magnetic Forces o Magnetic forces act on certain metals, on the poles of magnets and on moving charges.
Nuclear Forces o Two forces- a strong and a weak nuclear force, act within the nucleus hold it together Strong Nuclear Force
- The strong nuclear force is a powerful force of attraction that acts only on the neutrons and protons in the nucleus, holding them together. The strong nuclear force acts over very short distances.
Weak Nuclear Force - The weak nuclear force is an attractive force that acts over a shorter range than
the strong nuclear force. Gravitation Forces
o Gravitational forces are an attractive force that acts between any two masses. o Newton’s law of universal gravitation states that every object in the universe attracts
every other object o The gravitational force between two objects is proportional to their masses and
decreases as the distance between them increases. o Gravity is the weakest universal force, but it is the most effective over long distances.
Earth, Moon and Tides A centripetal force is a center directed force that continuously changes the direction of an object to make it move in a circle. This force causes the moon to orbit the Earth This gravitational pull from the moon produces two bulges in the Earth’s oceans. These bulges produce the high and low tides each day.
MOTION
• How do you know something is moving? o Depends on your ______________ ____ _____________________. o To describe motion accurately and completely, a frame of ________________ is
necessary o The frame of reference is the ______________ from which motion is ______________. o Most common: the __________.
How fast are you moving?
• _________________ motion is movement in relation to a frame of reference.
• You must choose a meaningful frame of reference to allow you to describe motion in a _____________ and relevant matter.
Measuring distance
• ________________: the length of a path between two points.
• When an object moves in a__________________ line, the distance is the length of the line
connecting the object’s _______________point and its __________________point.
• Distance tells you how far an object has moved. It does not depend on direction.
• Distance is a _______________ quantity. o Magnitude (how ________) o No ____________required
• Choose a unit that is best suited for the motion being described.
• SI unit for measuring distance is ______________.
• Examples: meters, kilometers, centimeters
Measuring displacement
• To describe an objects position relative to a given point, you need to know how far away and in what direction the______________is from that point.
• Displacement is independent of the path taken by the object.
• Displacement is the direction from the starting point and the length of a straight line from the starting point to the ending point.
Combining Displacements
• Displacement is an example of a ________________.
• A vector is a quantity that has ________________ and __________________.
• The magnitude can be ________, _______________or__________________.
• __________________ on a graph or map are used to represent vectors.
• The_____________ of the arrows shows the magnitude of the vector.
• Vector addition is the _____________________ of vector magnitudes and directions.
Adding vectors
• When the vectors are along the same plane they are _______________ arithmetically.
Name ____________________________________ Date ____________________ Block __________
• Many different methods for adding vectors that do not lie in the same plane.
A physical science student runs in the path shown below. How far did he run? What was his final
displacement?
The diagram shows the path of a cross country skier. Point A is the starting point. According to the
diagram, what distance did she travel while skiing? What was her final displacement?
What is the difference between distance and displacement?
What units would you use to express distance?
Displacement?
Can you think of a scenario where an object moves a certain
distance, but has a displacement of zero?
What is SPEED?
• The _____________ of distance an object moves to the amount of time it takes to move that distance.
• How fast or slow an object is traveling.
• Is speed a vector or a scalar quantity
Average Speed
• Defined as the total distance / total time. Or V = d/t
Instantaneous speed
• Not as useful in physical science. Much more difficult to calculate.
• Defined as the ______________at a given moment in time. • A s_______________ gives you instantaneous speed
Graphing motion
• Distance-time graphs.
• The slope of a line on a distance-time graph is the ______________.
• Using the graph on the slide… what speed is the student walking down the hallway?
Velocity
• The speed and direction in which an object is moving is called _______________.
• Velocity is a description of both _________and direction of____________.
• Velocity is a v___________.
• A change in velocity can be the result of a change in ____________, a change in ____________, or both.
Speed vs velocity
• Velocity is speed in a given direction.
• MUST have a direction.
• Considered a vector quantity
Combining Velocities
• This is done when the motion of an object involves more than one velocity
What is acceleration?
• _______________________ is the rate at which velocity changes.
• Acceleration can be described as changes in _______, changes in ______________ or changes
in________________.
• “Speeding up or slowing down”
• “changing direction”
• Science definition: the rate of change of velocity
• Can be both negative and positive
• Acceleration is a VECTOR quantity..
• The distance-time graph for acceleration is always a curve.
What is the formula for acceleration?
• Acceleration = final velocity – original velocity Time
• Or the change in velocity ( v) / time (∆t)
• Label : m/sec/sec or m/sec2
Example problems:
• A roller coaster’s velocity at the top of a hill is 10 m/sec. Two seconds later it reaches the bottom of the hill with a velocity of 26 m/sec. What is the acceleration of the roller coaster?
• A roller coaster is moving 25 m/sec at the bottom of a hill. Three seconds later it reaches the top of the hill and is traveling at a speed of of 10 m/sec. What was the roller coaster’s acceleration?
• Can you have negative acceleration? YES. The negative sign tells us the direction of the acceleration, usually means deceleration.
Free Fall
• The movement of an object toward Earth solely because of gravity
• All objects fall at the __________ rate
• ______ m/sec2
Graphing acceleration
• Distance-time graph for constant acceleration always a __________________.
• Velocity-time graph for constant acceleration always a ____________ ____________
The graph below is a __________________________________________
The graph below is a __________________________________________
Changes in Direction
❖ ___________________ isn’t always the result of changes in speed. You can accelerate even if your
speed is _________________. You experience this type of acceleration if you ride a bicycle around a
curve.
Changes in Speed and Direction
❖ Sometimes motion is characterized by changes in both speed and direction at the
___________________time. You experience this type of motion if you ride on a roller coaster like the
one on the next slide. It stats our slowly as the cars travel up the steep incline and then they reach
the top and plummet to the ground and whip around a curve. You are thrown backwards, forwards
and sideways as your velocity increases, decreases and changes direction. Your acceleration is
constantly ___________________.
Constant Acceleration
❖ Constant acceleration is a steady change in ___________________. The velocity of the object
changes by the same about each ___________________. An example is an airplane’s acceleration on
a portion of its take off.
Calculating Acceleration
❖ ______________________ is the rate at which velocity changes.
❖ You calculate ______________________ for straight-line motion by dividing the change in velocity by
the total time.
❖ _______________ = change in velocity = (vf – vi)
Total Time t
In the formula above, velocity is in the numerator and time is in the denominator.
❖ If the ______________ increases, the numerator is ______________ and thus the acceleration is also
positive. For example if you are coasting downhill on a bicycle, your velocity increases and your acceleration
is positive. If the velocity ______________, then the numerator is ______________ and the acceleration is
also negative. For example, if you continue coasting after you reach the bottom of the hill, your velocity
decreases and your acceleration is negative.
❖ Remember that acceleration and velocity are both ______________ quantities. If an object moving at
constant speed ______________ its direction of travel, there is still acceleration. In other words, the
acceleration can occur even if the ______________ is constant. Think about a car moving at a constant speed
as it rounds a curve. Because its direction is changing, the car is accelerating.
❖To determine a change in velocity, subtract one velocity vector from another. If the motion is in a straight
line, however, the velocity can be treated as ______________. You can then find acceleration from the
change in speed divided by the time.
Acceleration
A flowerpot falls off a second-story windowsill. The flowerpot starts from rest and hits the
sidewalk 1.5 s later with a velocity of 14.7 m/s. Find the average acceleration of the flowerpot.
1. List the given and the unknown values.
Given: time, t = 1.5 s
initial velocity, vi = 0 m/s
final velocity, vf = 14.7 m/s down
Unknown: acceleration, a = ? (m/s2 and direction)
2. Write the equation for acceleration.
acceleration = change in velocity = (vf – vi)
Total Time t
3. Insert the known values into the equation, and solve.
a = 14.7m/s – 0m/s
1.5s
a = 9.8 m/s2
Graphing Accelerated Motion
〉The slope of a straight line on a speed vs. time graph is equal to the acceleration.
Speed-Time Graphs
〉How can a graph be used to find acceleration? For example, consider a
downhill skier who is moving in a straight line. After traveling down the
hill for 1 second, the skier’s speed is 4 meters per second. In the next
second, the speed increases by an additional 4 meters per second, so the
skier’s acceleration is 4 m/s2.
〉_______________acceleration is represented on a speed-time graph by
a straight line. The graph is an example of a ________________ graph, in
which the displayed data form straight-line parts. The slop of the line is
the acceleration.
❖Constant _______________ acceleration decreases speed. The speed
time graph to the right shows the motion of a bicycle slowing to a stop. The
horizontal line segment represents_______________ speed. The line
segment sloping _______________represents the bicycle slowing down.
The change in speed is _______________, so the slope of the line is negative.
Graphing Accelerated Motion
❖__________________ can also be seen on a distance vs. time
graph.
❖The distance vs. time graph is not a ______________ line when
the velocity is not constant.
❖This ______________ line indicates that the object is under
______________.
Graphing Skills
Graphing Acceleration
A bus traveling on a straight road at 20 m/s uniformly slows to a stop over 20 s. The bus remains
stopped for 20 s, then accelerates at a rate of 1.5 m/s2 for 10 s, and then continues at a constant speed.
Graph speed vs. time for 60 s. What is the bus’s final speed?
1. Determine the x-axis and the y-axis of your graph.
The x-axis will indicate time, t, measured in s. The y-axis will indicate speed, v, measured in m/s.
2. Starting from the origin, graph each section of the motion.
A. Draw and connect the first two points:
t = 0 s, v = 20 m/s
t = 20 s, v = 0 m/s
B. Draw a horizontal line from t = 20 s to t =
40 s at v = 0 m/s.
C. Starting at t = 40 s and v = 0 m/s, draw a
line with a slope of 1.5 m/s2.
D. Draw a horizontal line from t = 50 s to t =
60 s at v = 15 m/s.
3. Read the graph to find the final speed.
At time t = 60 s, the speed is 15 m/s.
Instantaneous Acceleration
❖Acceleration is rarely ______________, and ______________ is rarely in a ______________ line.
____________________________ acceleration is how fast a velocity is changing at a specific instant
❖Acceleration involves a change in ______________or ______________ or ______________, so the vector of
the acceleration can point in any direction.
Forces and Motion
What is Force?
• A _________or _________ that acts on an object
• Can cause a _________ object to move
• Can accelerate a moving object
– By changing its ________ or ________
How is force measured?
• Spring scale
– Stretch of the spring depends on the _____ of the object acting on it
• Unit of Force
– Newton (N) – 1 kg to accelerate 1 m/s2
–
How is force represented?
• Use arrows
– Direction
– Strength
• Length represents strength or magnitude – The scale with more apples, greater mass, has a longer
arrow. The arrow is pointed downward due to mass is
below the balance pulling downwards.
Combining Forces
• Forces in the same direction are _________ together
• Force in the ________ direction are subtracted
• Net Force
– Overall force acting on an object
Balanced vs. Unbalanced Forces
• Balanced
– Combine to produce a net force of ______
– No change in the object’s motion
• Unbalanced
– Net force equals the size of the ______ force minus the size of the _______ force
– Net force does not equal _______
– Causes an object to _______________
Representing Forces
Adding Forces
Subtracting Forces
Equal and opposite forces
So in the case above, you’d add 100 N + 90 N and get 190 N to the right. You KNOW it’s being pulled 180 N to
the left. The notes says forces in the opposite direction are subtracted. So you subtract 190 N – 180 N and
get a net force of 10 N and the box would move to the right. It would mean its unbalanced because the net
force doesn’t equal zero.
Because these two have equal forces acting on it, the net force is zero.
Friction
• Force that __________ the motion of objects that touch as they move past each other
• Acts at the ____________ where objects are in contact
• ___ types of friction
4 Types of Friction
Static friction (pictured right)
– Force that acts on objects that are not __________
– Always acts in the direction ________to that of the applied force
Sliding friction
– Force that ________ the direction of motion of an object as it slides over a surface
Rolling friction
– Change in ________ at the point of rolling contact
Fluid friction
– Opposes the motion of an object through _________
– _________ the speed of the object moving through the fluid – Fluids (____ and __________)
Gravity
• Force that acts between two _________
• Attractive force
– Pulls objects __________
• Earth’s gravity • Acts __________ towards the center of the earth
Gravity and Falling Objects
• Gravity causes objects to ___________ downward
• _____ __________ (fluid friction) acts in the direction opposite to the motion and reduces acceleration
• Terminal velocity – Constant velocity of a _________ object when force of resistance equals _________
Projectile Motion
• Motion of a falling object after given an initial ___________ _____________
• Causes a curved path
Newton’s 1st Law of Motion
• Law of inertia
– Inertia
• Tendency of an object to ________ change in its motion
• State of an object does not _________ as long as the net force acting on it is zero
• An object at _______ stays at rest, an object in motion stays in ________ at the same direction
and speed (until something acts on it)
Newton’s 2nd Law of Motion
• The _________________ of an object is equal to the net force acting on it divided by the object’s mass
• Mass - Measure of _________ of an object and depends on the amount of matter the object contains
• The acceleration of an object is always in the same direction as the _____ _________
• Net forces in the _____________ direction of object’s motion
– Force produces deceleration and reduces _________ Ex. Seat belts
• Units for Acceleration are equivalent
N/kg = m/s2
An example of Newton’s Second Law is when we use crash-test dummies. Dummies are used in simulated car crashes to study what might happen to passengers in a real crash. They
are fitted with a range of measuring devices that tract the motion of the dummies throughout the crash. By
analyzing the data, scientists learn how injuries occur and how they can be prevented. What forces act on the
crash-test dummy to slow its forward movement?
Weight and Mass
• Weight & Mass are Different
• Weight
– The force of __________ acting on an object
– Product of the _______ and _______________ due to gravity
– Unit is Newtons (N)
Mass is a measure of the ______________of an object; weight is a measure of the force of _________ acting on
an object
Newton’s 2nd Law of Motion
1.A boy pushes forward a cart of groceries with a total mass of 40.0 kg. What is the acceleration of the
cart if the net force on the cart is 60.0 N?
a=F/m
= 60.0 N/40.0 kg
= 1.50 m/s2
2. What is the upward acceleration of a helicopter with a mass of 5000 kg if a force of 10,000 N acts
on it in an upward direction?
a=F/m
= 10000 N/5000 Kkg
= 2 m/s2
3.An automobile with a mass of 1200 kg accelerates at a rate of 3.0 m/s2 in the forward direction. What
is the net force acting on the automobile? (Hint: Solve the acceleration formula for force.)
F=ma
4.A 25-N force accelerates a boy in a wheelchair at 0.5 m/s2 What is the mass of the boy and the
wheelchair? (Hint: Solve Newton's second law for mass.) m=F/a
Newton’s 3rd Law of Motion & Momentum
• 3rd Law – when an object exerts a _________ on a second object, that object exerts an equal and
_____________ force on the first object
• Momentum
– Product of an object’s mass and its ___________
– Objects momentum at rest is ______
– Unit kg m/s
The two forces are called ________ and ___________ forces.
According to Newton’s 3rd Law, there must be an ________ and __________ reaction force.
Not all action and reaction forces produce___________. Only when equal and opposite forces act on the same object do they result in a net force of________.
Law of Conservation of Momentum
• If no net force acts on a system, then the total __________ of the system does not change
• In a ________ system, loss of momentum of one object equals the ______ in momentum of another object
Universal Forces • Four different forces exist throughout the universe. – _____________________ – _____________________ – _____________________ – _____________________ – All the universal forces act over a ___________ between particles of matter, which means the
particles do not need to be in_____________ with one another.
Universal Forces Electromagnetic Forces – Electromagnetic force is associated with ______________ _________________ – Electric forces and magnetic forces are the only forces that can both _________ and ________ Electric forces – Electric forces act between charged objects or particles such as _________ or ___________ – Objects with ________ charges _______while objects with ___________charges _________ Magnetic Forces o Magnetic forces act on certain __________, on the poles of magnets and on moving charges. Nuclear Forces o Two forces- a strong and a weak nuclear force, act within the ___________ hold it together Strong Nuclear Force
- The strong nuclear force is a powerful force of attraction that acts only on the ________ and _____________ in the nucleus, holding them__________. The strong nuclear force acts over very __________ distances.
Weak Nuclear Force
- The weak nuclear force is an attractive force that acts over a __________range than the strong nuclear force.
Gravitation Forces o Gravitational forces are an attractive force that acts between any two ____________. o Newton’s law of universal gravitation states that every ____________ in the universe attracts
every _____________ _______________ o The gravitational force between two objects is proportional to their _____________ and
______________ as the ____________ between them________________. o Gravity is the ______________ universal force, but it is the most effective over long
__________________.
Earth, Moon and Tides A __________________ force is a center directed force that continuously changes the direction of
an object to make it move in a _________________. This force causes the _________to orbit the ____________ This gravitational pull from the moon produces two _____________ in the Earth’s __________. These bulges produce the ____________ and low ____________ each day.
Test # Type (Prefix, Root or
Suffix) Root or Affix Meaning Example
12 root lab work laboratory
12 root lac milk lactation
12 root latry worship idolatry
12 root lapid, lapis stone dilapidated
12 root laps slip elapsed, lapsed
12 root later side latissimus, lateral
12 root lav, lava wash, bath lavatory, absolute
12 root laud to praise applaud, plaudits, cum laude
12 root leg law legal, legislature
12 root lev, life, live light, lift levity, levitate, elevator
12 root liber free, book liberal, library, liberty
12 root lic, linqu leave, forsake, permit license, relinquish, elicit
12 root lingua tongue linguistics
12 root lith, litho stone, rock monolith, lithography
12 root locus place locality, local, circumlocution
12 root log, logue, logo word, thought dialogue, monologue
12 root luc, lus lux, lum, lumen light, shine lucid, luminous
12 root lud, lus play, deceive elude, elusive
12 root luna, luni moon lunar eclipse
12 root lust shine luster
Name _________________________________________ Date ____________________ Block ________ Test # ________ (Fill this in!!)
Type (Prefix, Root
or Suffix) root or affix meaning examples
SPEEDThe rate of change of the
position of an object.
S = D ÷ TMeasured in units ofm/s or km/h
TIMEA limited period or interval, as between two successive events.
T = D ÷ SMeasured in units of
Seconds (s)or
Hours (h)
D
T S×÷ ÷
DISTANCEThe interval between two
points of position.
D = T × SMeasured in units ofKilometers (km)
orMeters (m)
TIME___________________________________________________________________________________________________________________________
SPEED___________________________________________________________________________________________________________________________
D
T S×÷ ÷
DISTANCE___________________________________________________________________________________________________________________________
V
A T×÷ ÷
TIMEA limited period or interval, as between two successive events.
T = V ÷ AMeasured in units of
Seconds (s)
ACCELERATIONThe rate at which the velocity of a body changes with time.
A = V ÷ TMeasured in units of
Meters persecond squared
m/s2
VELOCITYThe rate of change of the position of an object in a
particular direction.
V = A × TMeasured in units ofMeters per second
m/s
TIME___________________________________________________________________________________________________________________________
ACCELERATION___________________________________________________________________________________________________________________________×
÷ ÷
VELOCITY___________________________________________________________________________________________________________________________
V
A T
DISTANCEThe interval between two
points of position.
d = W ÷ FMeasured in units ofKilometers (km)
orMeters (m)
FORCEA push or a pull upon an object
resulting from the object’s interaction with another object.
F = W ÷ dMeasured in units of
Newtons (N)1N = 1kg × m/s2
W
F d×÷ ÷
WORKThe amount of force applied to
an object over a specific distance.
W = F × dMeasured in units of
Joules (J)1J = 1kg × m2/s2
DISTANCE___________________________________________________________________________________________________________________________
FORCE___________________________________________________________________________________________________________________________×
÷ ÷
WORK___________________________________________________________________________________________________________________________
W
F d
ACCELERATIONThe rate at which the velocity of a body changes with time.
a = F ÷ mMeasured in units of
Meters persecond squared
m/s2
F
m a×÷ ÷
MASSThe amount of matter that an object or substance contains.
m = F ÷ aMeasured in units of
Grams (g)
FORCEA push or a pull upon an object resulting from the object’s interaction with
another object.
F = m × aMeasured in units of
Newtons (N)1N = 1kg × m/s2
ACCELERATION___________________________________________________________________________________________________________________________
MASS___________________________________________________________________________________________________________________________×
÷ ÷
FORCE___________________________________________________________________________________________________________________________
F
m a
