Exam 2

Question 1

Convert kg to g

convert mg to g
3mg convert to grams

Answer 1

1. 1 kg is = to 1000 g

2. g times 10 to the negative 3

Question 2

Electronegativity __________ across a period

and _____________ down a column

Answer 2

increases

decreases

Question 3

A _______ electronegativity difference leads to a higher bond polarity. A ________ electronegativity difference leads to a lower bond polarity

Answer 3

higher

lower

Question 4

What is a dipole moment

Answer 4

it occurs anytime there is a separation of positive and negative charge

Question 5

As bond order __________ the bond gets stronger (Greater bond energy)
and that results in __________ (shorter or longer) bond lengths

Answer 5

increases

shorter

Question 6

bonding between a metal and nonmetal

bonding between a nonmetal and nonmetal

Answer 6

ionic bonding

covalent bonding

Question 7

In the band theory, what do you call the molecular orbitals that are occupied

what do you call the orbitals that are unoccupied

Answer 7

valence band = occupied

conduction band = unoccupied

Question 8

When there is no energy gap between the conduction band and valence band what does that mean

When there is a small energy gap between the conduction band and valence band

When there is a large energy gap between the conduction band and valence band what does that mean

Answer 8

conductor

semiconductor

insulator

Question 9

What is a molecular compound

Answer 9

2 or more nonmetals = covalent bond only

Question 10

What are the rules for naming a molecular compound

Answer 10

1. identify it as a molecular compound
2. write name of element with smallest group number first
3. If the two elements lie in the same group, write element with greatest row number first

Question 11

What is the form for writing a molecular compound name

Answer 11

prefix (if needed) - Name of first element (smallest group #) - prefix of second element - base name of second element plus -ide

Question 12

What is the name of NO2

N20?

NI3

Answer 12

1. Nitrogen dioxide
2. dinitrogen monoxide
3. Nitrogen triiodide

Question 13

Write formula for Phosphorus tribromide

Answer 13

PBr3

Question 14

what is the atomic mass?

Answer 14

average mass of atom

Question 15

What is the formula mass

what is it also called?

Answer 15

average mass of molecule of a compound

molecular mass or molecular weight

Question 16

How do you get formula mass?

Answer 16

[(number of atoms of 1st element in chem formula) times (atomic mass of first element)] + [(number of atoms of 2nd element in formula) times (atomic mass of first element)] etc….

Question 17

What is the formula mass for CO2

Answer 17

C= 12.01 0=16

Formula mass= 12.01+ (2*16)= 44.01

Question 18

What is the molar mass of a compound

Answer 18

mass in grams of one mol of its molecules or formula units - numerically equivalent to its formula mass 5.9

Question 19

Find number of CO2 molcules in a sample of dry ice (solid CO2) with mass of 10.8 g

Answer 19

Plan:
grams CO2 to moles of CO2 to CO2 moledcules (remember to use the avogardo number when converting to molecules)

should get 1.48 times 10 to the 23 CO2 molecules

Question 20

what do you use avogardo number for

Answer 20

for converting any compound of moles to molecules

Question 21

What is mass percent

how do you find it

Answer 21

mass %= percent of compounds total mass

find it by
mass% of element x within a given compound = mass of element x in one mol of compound divided by mass of 1 mol of compound

Question 22

CCl2F2 calc mass % of Cl

Answer 22

mass % Cl=

first find molar mass of whole thing
than take Cl molar mass divided by entire molar massthen times by 100=
58.64%

Question 23

what are organic compounds composed of

Answer 23

carbon and hydrogen

Question 24

What is the key element in organic compounds

Answer 24

Carbon because always form four bonds

Question 25

organic vs inorganic

Answer 25

``` organ= living in= originate from earth ```

Question 26

what are hydrocarbons

Answer 26

simpelest organic compounds / composed of hydrogen and carbon

Question 27

does a pair of electrons have to be shared equally amongst compound

Answer 27

no unequal results in polar covalent bonds

Question 28

what is electronegativity

Answer 28

ability of an atom to attract electrons to itself in a chem bond (results in polar and ionic bonds)

Question 29

what does polar covalent mean

Answer 29

there is an intermediate electronegative difference between the two atoms (one has more of electron than other)

Question 30

What is purely covalent

Answer 30

bond where electrons are equally shared

Question 31

what is a dipole moment

Answer 31

occurs anytime there is a seperationof positive and negative charge

Question 32

what is percent ionic character

Answer 32

ratio of bond's actual dipole moment to the dipole moment it would have if the electron were completely transferred from one atom to the other times 100

Question 33

The smaller the magnitude of the charge separation and the smaller the distance between the charges, the smaller the dipole moment

Answer 33

true

Question 34

if an electron is completely transferred from one atom to another what would the % ionic character be

Answer 34

100%

Question 35

percent ionic character _____________ (inc. or dec.) as the electronegativity difference ________ (inc. or dec.)

Answer 35

inc. | inc

Question 36

what is the bond energy

Answer 36

of a chem bond it is the energy required to break one mole of the bond in the gas phase

Question 37

what are the 5 basic shapes according to the number of electron groups surrounding a central atom and their bond angles

Answer 37

1. linear (2) ...180 2. trigonal planar (3). 120 3. tetrahedral (4)... 109.5 4. trigonal bipyrimidal (5)..... 120/90 5. octahedral (6).... 90

Question 38

When a triangular (trigonal ) planar has one lone pair and two bonded pairs what molecular geo does it take on

Answer 38

eg= triangular planar mg= bent or angular

Question 39

Tetrahedral molecular geo when one lone pair two lone pairs

Answer 39

one= triangular pyramidal two= bent or angular

Question 40

triangular bipyrimidal one lone pair two lone pairs three lone pairs

Answer 40

one= see saw two= t shaped three= linear

Question 41

octahedron with one lone pair two lone pairs

Answer 41

``` one= square pyramidal two= square planar ```

Question 42

what are magnetic properties a result of

Answer 42

due to electrons | unpaired elecrons cause magnetism

Question 43

what is the flaw in the lewis structure

Answer 43

does not predict magnetic properties

Question 44

what is the valence bond theory

Answer 44

a chem bond is overlap between two half filled atomic orbitals

Question 45

______________ (higher or lower) bond order= ____________ (weaker or stronger) bond

Answer 45

higher | stronger

Question 46

what is the formula for bond order

Answer 46

of electrons in bonding Molecular oribitals - number of electrons in antibonding molecular orbitals all divded by two

Question 47

if 1 or higher than compound is considered stable?

Answer 47

true

Question 48

what is earth's most significant greenhouse gas

Answer 48

cabon dioxide

Question 49

what does CO2 doe to the atmosphere

Answer 49

enhances ability to hold heat = global warming

Question 50

chem change vs physical change

Answer 50

``` chem= atoms rearrange ex= rusting iron, burning sugar, transformation of oxygen and CO2 to glucose ``` phys= no change in arrangement ex boiling water, changing state of matter, physically crushing something

Question 51

what are some guidelines for balancing equations

Answer 51

start withmost complex comound first | and to clear fraction times by denominator to everything in reactant

Question 52

stoichiometry analougy is what

Answer 52

recipies ex pizza