Chemistry Midterm ReviewChemistry Midterm Review

DeMario 2007DeMario 2007

Question OneQuestion One

Describe the atomic model for each Describe the atomic model for each scientist listed. Be sure to mention scientist listed. Be sure to mention information about the experiment and information about the experiment and the location of the subatomic particles.the location of the subatomic particles.

1.1. DaltonDalton

2.2. ThomsonThomson

3.3. RutherfordRutherford

4.4. BohrBohr

5.5. Modern ViewModern ViewAnswer

Answer 1Answer 1 Dalton – indivisible, solid sphere (no subatomic Dalton – indivisible, solid sphere (no subatomic

particles)particles) ThomsonThomson- “plum pudding model” electrons are - “plum pudding model” electrons are

evenly distributed throughout a mass of protons. evenly distributed throughout a mass of protons. Model based on his cathode ray experimentModel based on his cathode ray experiment

RutherfordRutherford- discovered mostly empty space - discovered mostly empty space surrounding a dense positively charged nucleus surrounding a dense positively charged nucleus using through the gold foil experimentusing through the gold foil experiment

BohrBohr- believed in a small positively charged nucleus - believed in a small positively charged nucleus containing the protons and neutrons surrounded by containing the protons and neutrons surrounded by electrons in ORBITS of specific energy levelselectrons in ORBITS of specific energy levels

Modern View-Modern View- Also called the wave- mechanical Also called the wave- mechanical model and the quantum model similar to Bohr but model and the quantum model similar to Bohr but electrons are in regions of high probability based on electrons are in regions of high probability based on energy level, and orbital. energy level, and orbital.

Question 2Question 2

Compare the charge, Compare the charge, size, and location of a size, and location of a proton, neutron, and proton, neutron, and electron.electron.

Answer 2

Answer 2Answer 2Type of Type of

subatomic subatomic particleparticle

Size in Size in amuamu Charge Charge Location in an Location in an

atomatom

ProtonProton 11 +1+1 nucleusnucleus

Neutron Neutron 11 00 nucleusnucleus

Electron Electron 1/2001/20000

-1-1

Electron clouds Electron clouds surrounding surrounding

nucleusnucleus

Question 3 Question 3

Explain why the following two Explain why the following two elements are isotopes. State the elements are isotopes. State the number of protons, electrons, and number of protons, electrons, and neutrons each isotope possesses.neutrons each isotope possesses.

Sn

Sn11950

12150

Answer 3 Answer 3

They are isotopes because each have They are isotopes because each have a different # of neutrons but the a different # of neutrons but the same number of protons and same number of protons and electrons.electrons.

Sn -121 has 50 pSn -121 has 50 p++, 50 e, 50 e--, 71 n, 71 n00

Sn- 119 has 50 pSn- 119 has 50 p++, 50 e, 50 e--, 69 n, 69 n00

Question 4Question 4

List the seven List the seven metalloids metalloids

Answer 4Answer 4

BB

Si, Si,

Ge, AsGe, As

Sb, TeSb, Te

AtAt

Question 5Question 5

Why is the formation of a Why is the formation of a solution a physical change solution a physical change while the ability to react while the ability to react with a chemical with a chemical considered a chemical considered a chemical change?change?

Answer 5Answer 5

““reacting” indicates a change in the reacting” indicates a change in the physical properties of an element physical properties of an element resulting in a new compound.resulting in a new compound.

Formation of a solution is a physical Formation of a solution is a physical property because a new compound has property because a new compound has not been formed. Evaporation of the not been formed. Evaporation of the water would leave the original water would leave the original compound behind. (ex. salt dissolving in compound behind. (ex. salt dissolving in water)water)

Question 6Question 6

List Properties of a List Properties of a metal and a metal and a nonmetal.nonmetal.

Answer 6Answer 6 MetalsMetals

Form cationsForm cations ShinyShiny MalleableMalleable DuctileDuctile Good conductorsGood conductors Low Low

electronegativites electronegativites and IEand IE

Solids except HgSolids except Hg

NonmetalsNonmetals BrittleBrittle DullDull Poor conductorsPoor conductors High High

electronegativitielectronegativities and IEes and IE

Question 7Question 7

Define Define allotrope.allotrope.

Answer 7Answer 7

One or more molecular forms of an One or more molecular forms of an element in the same physical state;element in the same physical state; Example: OExample: O2 2 and Oand O33

Carbon: graphite, diamond, Carbon: graphite, diamond,

buckyballsbuckyballs Allotropes are composed of the same Allotropes are composed of the same

element but different composition of atoms element but different composition of atoms results in different properties and different results in different properties and different structures.structures.

Question 8Question 8

What is the What is the correct formula correct formula for Cobalt(III) for Cobalt(III) bromide?bromide?

Answer 8Answer 8

CoBrCoBr33

Question 9Question 9

What form of What form of matter cannot matter cannot be decomposed?be decomposed?

Answer 9Answer 9

ElementElement

Question 10Question 10

What happens to a What happens to a nonmetal ion when it nonmetal ion when it becomes a negative ion?becomes a negative ion?Mention difference in # Mention difference in # of electronsof electrons

Changes in radiusChanges in radius

Answer 10 Answer 10

Gains electronsGains electronsRadius increasesRadius increases

Question 11Question 11

What is the name of the What is the name of the property that indicates property that indicates an element’s desire to an element’s desire to attract electrons and attract electrons and which element has the which element has the greatest attraction?greatest attraction?

Answer 11Answer 11

ElectronegativElectronegativityity

FluorineFluorine

Question 12Question 12

What are the terms used to What are the terms used to identify a pure substance?identify a pure substance?

What are the terms used to What are the terms used to identify a mixture?identify a mixture?

Answer 12Answer 12

Element and Element and compoundcompound

Heterogeneous and Heterogeneous and HomogeneousHomogeneous

Question 13Question 13

What is the difference What is the difference between an excited between an excited state electron and a state electron and a ground state electron?ground state electron?

Answer 13Answer 13

Ground state electrons are in the Ground state electrons are in the lowest energy statelowest energy state

Excited state electrons have Excited state electrons have absorbed energy allowing them to absorbed energy allowing them to jump to a higher energy level.jump to a higher energy level.

Question 14Question 14

What are the three What are the three assumptions made assumptions made regarding particle regarding particle

behavior in the KMT behavior in the KMT [Kinetic Molecular [Kinetic Molecular

Theory]?Theory]?

Answer 14Answer 14

1.1. Gas particles are small, hard Gas particles are small, hard spheres with insignificant volumesspheres with insignificant volumes

2.2. Particle’s motion is rapid, Particle’s motion is rapid, constant, and random straight-line constant, and random straight-line motionmotion

3.3. Particle collisions are perfectly Particle collisions are perfectly elasticelastic

Question 15Question 15

What is the name for each type of What is the name for each type of phase change?phase change?

1.1. SolidSolid liquid liquid

2.2. Liquid Liquid gas gas

3.3. Gas Gas liquid liquid

4.4. Liquid Liquid solid solid

5.5. Solid Solid gas gas

Answer 15Answer 15

1.1. MeltingMelting

2.2. Boiling or vaporizationBoiling or vaporization

3.3. CondensationCondensation

4.4. Freezing / solidificationFreezing / solidification

5.5. SublimationSublimation

Question 16Question 16

According to Avogadro's According to Avogadro's Hypothesis two samples of Hypothesis two samples of gas that have the same gas that have the same volume and are at the same volume and are at the same temperature and pressure temperature and pressure will _______________.will _______________.

Answer 16Answer 16

Have the same Have the same numbers of numbers of particlesparticles

Question 17 Question 17

Thermal energy from Thermal energy from a cold pack travels in a cold pack travels in which direction when which direction when applied to the leg?applied to the leg?

Answer 17Answer 17

Hot Hot cold cold

Leg Leg cold cold packpack

Question 18Question 18

Under what Under what conditions will a conditions will a real gas behave real gas behave

ideally?ideally?

Answer 18Answer 18

High temperature [so that High temperature [so that the particles are moving the particles are moving fast]fast]

Low pressure [ so that Low pressure [ so that particles are far apart to particles are far apart to avoid attraction]avoid attraction]

Question 19Question 19

What is the % What is the % composition by mass composition by mass of carbon in carbon of carbon in carbon dioxide [gram-formula dioxide [gram-formula mass 44 grams/mole]?mass 44 grams/mole]?

Answer 19Answer 19

27 % C27 % C

Question 20Question 20

Why does calcium Why does calcium have similar have similar chemical properties chemical properties to barium?to barium?

Answer 20Answer 20

Both are Group 2 Both are Group 2 elementselements

Both have the same Both have the same number of valence number of valence

electronselectrons

Question 21Question 21 Which of the following terms Which of the following terms

indicate a chemical property and indicate a chemical property and which indicate a physical property?which indicate a physical property?

1.1. FlattenFlatten

2.2. ConductConduct

3.3. CorrodeCorrode

4.4. Drawn into a wire Drawn into a wire

5.5. ReactReact

Answer 21Answer 21

Chemical Chemical CorrodeCorrode reactreact

Physical Physical Flatten Flatten DrawnDrawnConductConduct

Question 22Question 22

What is the What is the charge on a I-charge on a I-127 nucleus?127 nucleus?

Answer 22Answer 22

+53+53

Question 23Question 23

Name the type of Name the type of element as it element as it

appears in the order appears in the order below.below.

Ge Ge K K Ar Ar Br Br

Answer 23Answer 23

Ge Ge K K Ar Ar Br BrMetalloid, metal, Metalloid, metal,

noble gas, nonmetalnoble gas, nonmetal

Question 24Question 24

How many How many electrons are electrons are contained in an contained in an CuCu2+ 2+ ion?ion?

Answer 24Answer 24

27 electrons27 electrons

Question 25Question 25

Which electron configuration Which electron configuration represents the electrons of represents the electrons of atom of sodium in the excited?atom of sodium in the excited?

1.1. 2-8-12-8-1

2.2. 2-8-22-8-2

3.3. 2-7-32-7-3

4.4. 2-7-22-7-2

Answer 25Answer 25

4. 2-7-24. 2-7-2

Question 26Question 26

If an element is shiny If an element is shiny and a good and a good conductor, what type conductor, what type of element is it?of element is it?

Answer 26Answer 26

MetalMetal

Question 27Question 27

Compare the number Compare the number of subatomic particles of subatomic particles

that compose N-14 that compose N-14 and F-19.and F-19.

Answer 27Answer 27

N-14N-14 Protons 7Protons 7 Electrons 7 Electrons 7 Neutrons 7Neutrons 7

F-19F-19 Protons 9Protons 9 Electrons 9Electrons 9 Neutrons 10Neutrons 10

F-19 has two protons, two more electrons, and three more protons than N-14

Question 28Question 28

Which of the following is Which of the following is a molecular formula?a molecular formula?

CHCH44

CC33HH66

Answer 28Answer 28

CC33HH66

Question 29Question 29

In what ratio, will a In what ratio, will a calcium ion calcium ion

combine with a combine with a phosphide ion?phosphide ion?

Answer 29Answer 29

CaCa33PP22

3:23:2

Question 30Question 30

What is the melting point of this What is the melting point of this substance?substance?

s

l

g

280 k

380 k

Answer 30Answer 30

280 k280 k

Question 31Question 31

Describe the difference Describe the difference between a particle between a particle diagram of a solid, diagram of a solid,

liquid, and gas.liquid, and gas.

Answer 31Answer 31

Solid particles are packed Solid particles are packed tightlytightly

Liquids are close but have Liquids are close but have some space for movementsome space for movement

Gases are far apartGases are far apart

Question 32Question 32

Compare the Compare the atomic radius of atomic radius of Ca to Mg and Sr.Ca to Mg and Sr.

Answer 32Answer 32

The atomic radius The atomic radius falls in the middle falls in the middle

of Mg and Sr.of Mg and Sr.

Question 33Question 33

State the trend for each of State the trend for each of the following properties the following properties across a period.across a period.Ionization EnergyIonization EnergyElectronegativity Electronegativity Atomic radiusAtomic radius

Answer 33Answer 33

IE and Electronegativity IE and Electronegativity increases across the increases across the periodperiod

Atomic Radius decreasesAtomic Radius decreases

Question 34Question 34

State the trend for each of State the trend for each of the following properties the following properties down a group.down a group.Ionization EnergyIonization EnergyElectronegativity Electronegativity Atomic radiusAtomic radius

Answer 34Answer 34

IE and Electronegativity IE and Electronegativity decreases across the decreases across the periodperiod

Atomic Radius increasesAtomic Radius increases

Question 35Question 35

Which segments represent an increase Which segments represent an increase in PE and which represent an in PE and which represent an increase in KE?increase in KE?

1

2

3

280 k

380 k

A

B

C

Answer 35Answer 35

1, 2, 3 show an increase in KE 1, 2, 3 show an increase in KE because the temperature is because the temperature is increasingincreasing

A, B, C show an increase in PE A, B, C show an increase in PE because temperature remains because temperature remains constant until the phase change constant until the phase change is complete.is complete.

Question 36Question 36

Is this a endothermic or exothermic Is this a endothermic or exothermic reaction?reaction?

1

2

3

280 k

380 k

A

B

C

Answer 36Answer 36

Endothermic Endothermic because energy because energy

is being is being absorbed. absorbed.

Question 37Question 37

Why do the formulas for Why do the formulas for calculating the heat of calculating the heat of fusion and the heat of fusion and the heat of

vaporization not include vaporization not include a change in temperature a change in temperature as one of the variables?as one of the variables?

Answer 37Answer 37

The temperature is not The temperature is not changing during a phase changing during a phase

change. (P.E. is change. (P.E. is increasing)increasing)

Question 38Question 38

Calculate the Calculate the number moles in number moles in 48 grams of CO.48 grams of CO.

Answer 38Answer 38

1.7 moles1.7 moles

Question 39Question 39

What is the What is the combined gas combined gas

law?law?

Answer 39Answer 39

2

22

1

11

T

VP

T

VP

Question 40Question 40

What is the What is the relationship relationship

between Celsius between Celsius and Kelvin? and Kelvin?

Answer 40Answer 40

Kelvin = Celsius temp + Kelvin = Celsius temp + 273273