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TRANSCRIPT
notes 2015.notebook
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October 06, 2015
Sep 2911:29 AM
Sep 119:25 AM
Vocabulary QUIZ:1. The total number of particles in the nucleus2. 1/12th of the mass of a carbon atom3. The weighted average mass of all the isotopes of a particular element4. A helium nucleus is the same as this, two protons and two neutrons5. An extra negative electron is the same as this6. The rays and particles emitted by uranium7. Unstable atoms under go this8. I'm "positive" this particle is in the nucleus9. This particle is like Switzerland10. Two atoms differ only in mass number but not atomic number, they must be_______________.
notes 2015.notebook
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October 06, 2015
Sep 1112:31 PM
Atom ModelsScientists wanted to understand how the atom looked
It was known that matter was neutral
It was known that matter had mass
They used these to ideas to come up with their models, however science changed as technology developed
Video
Sep 109:05 AM
Who
Was
Right?Democritus and Leucippus- Greek philosophers who
came up with the concept of an “atom” from the Greek
word atomos which means indivisible.
History of Atomic Theory
Aristotle - Famous philosopher who believed that all substances were made of 4 elements: Fire – Hot, Air – light, Earth - cool, heavy, and Water – wet. Blend these in different proportions to get all substances
OR
ΕΡΛΨ ΓΡΣΣΚ ΘΟΤ
notes 2015.notebook
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October 06, 2015
Sep 1012:20 PM
In medieval times, alchemists began experimentation. They are known for trying to change lead to gold. Out of this practice emerged the modern chemists, the first being Sir Robert Boyle in the 1600s.He was the first to do actual chemical experiments. He helped end the idea of the four elements.
Medieval Times
Sep 101:04 PM
Late 1700’s - John Dalton, an English school teacher, summarized results of his experiments and those of other scientists. His conclusions led to the first scientific theory of the atom.
What is a scientific theory?
notes 2015.notebook
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October 06, 2015
Sep 101:07 PM
Dalton’s Atomic Theory1. All matter is made of tiny indivisible particles called
atoms. 2. Atoms of the same element are identical, those of
different elements are different. 3. Atoms of different elements combine in whole
number ratios to form compounds. 4. Chemical reactions involve the rearrangement of
atoms. No new atoms are created nor destroyed.
Sep 101:10 PM
MODERN VIEWS of the ATOM
Atom: The smallest particle of an element that retains the properties of the element.
Most atoms consists of three particles:• proton• neutron• electron
notes 2015.notebook
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October 06, 2015
Sep 58:04 PM
History of the AtomPlum Pudding model:
(J. J. Thomson in 1897)Spherically shaped
Electrons (negatively charged) positioned throughout it like chocolate chips in a cookie
The sphere was a positively charged mass, like the cookie dough Idea did not last long
Video
Sep 58:58 PM
History of the AtomErnest Rutherford (1911)Shot a beam of radiation particles at a thin sheet of goldHe expected the particles to go straight through if the atom was based off the Plum Pudding Model. Particles should only alter course if they hit an electron in the atom
notes 2015.notebook
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October 06, 2015
Sep 69:04 AM
History of the AtomErnest Rutherford (1911)The atom was made up of mostly empty space where the electrons movedThe positive charge of the atom was within the center of the atom: The nucleusa small dense positively charged space at the center of an atom
Electrons are held within the atom due to the attraction of the nucleusThe diameter of the atom was calculated to be 10,000 times the diameter of the nucleus (comparison: if the diameter of the nucleus was the size of my desk (1.34 m), how big would the diameter of the atom be?) in miles? 0.62 miles=1km
Sep 69:11 AM
History of the AtomJames Chadwick
Video
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October 06, 2015
Sep 69:11 AM
History of the AtomThe Nucleus contains protons and neutrons, containing 99.97% of the atoms massProtons are a positively charged subatomic particleNeutrons are neutrally charged subatomic particle
Nucleus is surrounded by negatively charged electrons, with negligible mass
Atoms are mostly empty space
Protons and electrons are attracted to each other
Video
Sep 78:13 AM
The Atom
CCarbon
6
12.011
Atomic Number
Element Symbol
Element Name
Atomic Mass
notes 2015.notebook
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October 06, 2015
Sep 78:13 AM
The Atom
CCarbon
6
12.011
Atomic Number
This tells you how many protons are in the atom (ALWAYS!!!)
The # of protons is the DNA of the atom, it makes it that element
This also tells you how many electrons there are in a neutral atom (remember protons are positive and electrons are negative
Sep 79:11 AM
The Atom
CCarbon
6
12.011
Atomic Mass
Atomic mass number of any one atom = # Protons + # NeutronsRemember Electrons mass is Negligible
12 amu 6 protons = 6 neutronsRound the mass to a whole number
Measured in Atomic Mass Units (AMUs)
notes 2015.notebook
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October 06, 2015
Sep 79:11 AM
The Atom
CCarbon
6
12.011
Average Atomic Mass (Why is this number not a whole number?)
This is the weighted sum of all the atomic masses possible for this element
Isotopes: Atoms with the same number of protons but different number of Neutrons
Since protons do not EVER change, and electrons mass is negligible, the only thing that can change the mass is a change in Neutrons
Oct 81:53 PM
notes 2015.notebook
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October 06, 2015
Sep 1310:21 AM
Writing isotopes
U
Uranium 238
23892
\ atomic #
mass number
Sep 1310:25 AM
Isotopesamu
oxygen 18
Bromine 80
Ba
p n e-
Li
Au
139
199
56
79
93
notes 2015.notebook
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October 06, 2015
Oct 82:10 PM
Sep 1310:25 AM
Isotopesamu
Nitrogen 15
Radon 222
Mo
p n e-
Ca
Ag
100
109
42
47
4120
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October 06, 2015
Sep 79:22 AM
The AtomAtomic Mass Calculation[% of Mass 1 x (Mass 1)] + [% of Mass 2 x (Mass 2)] +...
Copper has two isotopes: 69.2% of all copper has a mass of 63 amus and 30.8% of all copper has a mass of 65 amus. What is copper's atomic mass?
Oct 28:45 AM
Tin (Sn) has four different isotopes. What is the average atomic mass of a sample of Tin that has 55.0% of its isotopes having 118 amus, 19.0% having 119 amus, 20.0% having 120 amus, and 6.0% having 121 amus?
Warm up 10/6/2015
notes 2015.notebook
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October 06, 2015
Oct 131:39 PM
Fusion
+
Fission
Radioactivity
+
Sep 111:14 PM
Splitting the AtomRadioactive decay occurs when an atom undergoes a nuclear reaction. The nucleus breaks apart into a more stable structure. When this happens particles and energy are released. These particles and energy are called radiation.
Three types of radiation:• alpha• beta• gamma
notes 2015.notebook
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October 06, 2015
Sep 1210:14 AM
Alpha RadiationAlpha radiation is a very weak form of radiation. It can easily be stopped by human skin or paper. In alpha radiation, alpha particles are given off.An alpha particle contains two protons and two neutrons (a helium nucleus). It carries a +2 charge.
22688Ra ⇒ 22286Rn + α
Oct 132:01 PM
Niobium94 undergoes alpha decay
Barium138 undergoes alpha decay
Alpha Radiation
Lead209 undergoes alpha decay
notes 2015.notebook
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October 06, 2015
Sep 129:07 AM
Beta Radiation
Beta radiation is a stronger form of radiation. It can be stopped by aluminum foil or an inch of acrylic. In beta radiation, beta particles are given off.A beta particle is a particle with a -1 charge
How does this happen?
146C ⇒ 147N + β- + neutrino
Sep 1211:08 AM
Beta radiation (cont.)
146C ⇒ 147N + β- + neutrino
A neutron decomposes into a positive proton and releases the negative portion as a negatively charged particle and the extra energy as a neutrino
notes 2015.notebook
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October 06, 2015
Oct 132:10 PM
Carbon 14 undergoes beta decay
Potassium40 undergoes beta decay
Strontium88 undergoes beta decay
Beta Radiation
Sep 1211:13 AM
Gamma radiation
Gamma radiation is the strongest form of radiation. It is deadly to life. It can be stopped by an inch of lead or a meter of concrete. It will not turn you into the Hulk.
notes 2015.notebook
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October 06, 2015
Sep 139:28 AM
In gamma radiation, a very unstable nucleus has too much energy. To become stable, the nucleus releases the energy in the form of gamma rays and also other particles (beta, alpha, and/or neutrons)
Gamma radiation
Oct 132:18 PM
Rubidium86 undergoes only gamma decay
Rubidium86 undergoes gamma decay and the releases a neutron
Rubidium86 undergoes gamma and alpha decay
Rubidium86 undergoes gamma and beta decay
Gamma radiation
notes 2015.notebook
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October 06, 2015
Oct 1412:28 PM
54Mn undergoes beta decay. What is the final product?251.
Antimony 122 goes through alpha decay and then a beta decay. What is produced?
2.
What new element is created by the beta decay of polonium 210?
3.
If I was produced by two beta decays, what was the original element?
128534.
Practice
Oct 69:12 AM