O Chem Exam 1

Front 1

What is a "resonance hybrid"

Back 1

A resonance hybrid is a set of more than one Lewis structures for the same substance that are equally as stable as one another. The actual molecule is really a sort of "average" of them all, resulting in partial bonds and partial charges.

Front 2

True or False: When the stability of a resonance hybrid is more than it's Lewis structures indicates, this is called "resonance stabilization energy"

Back 2

True.

Front 3

What does this arrow mean?
↔

Back 3

Resonance arrow

Front 4

Define "electronegativity"

Back 4

Electron attracting ability. Atoms that are more electronegative will "pull" atoms more, resulting in uneven distribution of the electrons (polar charges)

Front 5

What is a "dipole"?

Back 5

When a positive and negative pole are present in a molecule.

Front 6

What is this?
µ = (e)(d)

Back 6

The equation for a "dipole moment", where µ = the value of the dipole moment, e = amount of charge separation, and d = distance of charge separation

Front 7

What does VSEPR stand for?

Back 7

Valence Shell Electron Pair Repulsion

Front 8

True or False: When the stability of a resonance hybrid is more than it's Lewis structures indicates, this is called "resonance equilibrium energy"

Back 8

False. When the stability of a resonance hybrid is more than it's Lewis structures indicates, this is called "resonance stabilization energy"

Front 9

What does this arrow mean?
→
←

Back 9

Equilibrium arrows

Front 10

True or False: All molecules that are shaped trigonal planar have a dipole.

Back 10

False.

Front 11

True or False: The presence of formal charges in a molecule is usually an indication of stability.

Back 11

False. The presence of formal charges in a molecule is usually a destabilizing factor.

Front 12

True or False. Hydrogen almost always has 1 or 2 bonds.

Back 12

False. Hydrogen almost always has 1 bond.

Front 13

Define "carbanion".

Back 13

An instance of a carbon atom with three bonds and 1 lone pair, giving it a negative charge

Front 14

Most organic compounds are based primarily on covalent bonds to __________.

Back 14

carbon

Front 15

True or False: Carbon commonly bonds to Hydrogen, Nitrogen, and Oxygen.

Back 15

True.

Front 16

What is a "constitutional isomer".

Back 16

Same atoms, different arrangement within the molecule.

Front 17

True or False. The presence of formal charges in a molecule is usually a destabilizing factor.

Back 17

True.

Front 18

True or False: Carbon commonly bonds to Bromine, Chlorine, and Astatine

Back 18

True. Carbon bonds easily with the halogens, especially Br, and Cl

Front 19

As the number of atoms in a formula increases, the number of possible constitutional isomers:
a) stays the same
b) decreases to 0
c) decreases by an indeterminate amount
d) increases dramatically
e) impossible to determine

Back 19

As the number of atoms in a formula increases, the number of possible constitutional isomers:
d) increases dramatically

Front 20

True or False: Carbon commonly bonds to Hydrogen, Oxygen, Nitrogen, Sulfur, and Phosphorus

Back 20

False. While carbon will bond and form stable compounds with S and P, it is not common.

Front 21

Define "ketone"

Back 21

Functional group containing a carbonyl group attached to two other carbon-containing functional groups (R & R')

Front 22

What is a "functional group"?

Back 22

A specific group of atoms within molecules that is responsible for the characteristic chemical reactions of those molecules.

Front 23

What is a "carbonyl group"?

Back 23

A carbonyl group is the functional group C = O (must be a double bond)

Front 24

Which of these is an example of a four carbon ketone in condensed form?
a) C6H6
b) CH3-CH2-C-O-CH3
c) OH-PO2H-OH
D) C2H60

Back 24

Which of these is an example of a four carbon ketone in condensed form?
b) CH3-CH2-C-O-CH3

Front 25

The ______________ provides useful information about possible molecular structures that will fit a molecular formula

Back 25

The degree of unsaturation provides useful information about possible molecular structures that will fit a molecular formula (useful for determining constitutional isomers)

Front 26

What is a "skeletal structure"?

Back 26

Quick way of diagramming organic compounds, where lines are assumed to have carbons at either end, and all necessary hydrogens are assumed to be present.

Front 27

True or False: Oxygen is ignored when calculating DU.

Back 27

True.

Front 28

Define "endothermic"

Back 28

Energy is added to the system.

Front 29

How is the degree of unsaturation calculated?

Back 29

DU = [(Maximum possible H's) - (Actual H's)] /2

Front 30

True or False: Hydrogen is ignored when calculating DU.

Back 30

False. Oxygen is ignored when calculating DU.

Front 31

Stronger covalent bonds tend to be _____________.

Back 31

Shorter. Also, they have higher "bond dissociation energy"

Front 32

Bonds between H and the second row elements C,N, and O are all __________.

Back 32

Strong. (or "short in length")

Front 33

True or False: chains of carbon and chains of nitrogen are common, but not oxygen.

Back 33

False. Chains of nitrogen are weak, and break easily. Chains of carbon are common, chains of nitrogen and chains of oxygen are not.

Front 34

What happens to carbon-halogen bonds as the atomic number of the halogen increases?

Back 34

The bond becomes weaker and longer.

Front 35

True or False: a carbon/carbon triple bond is 3 times as strong as a carbon/carbon single bond.

Back 35

False. Double bonds are not exactly twice as strong as single bonds, and triple bonds are not exactly three times as strong.

Front 36

True or False: Spherical molecules have more surface area than rod-shaped molecules, so their boiling points are slightly higher.

Back 36

False. Rod-shaped molecules have more surface area than spherical molecules, so their boiling points are slightly higher.

Front 37

What is an "alkyl group"?

Back 37

Group of SINGLY BONDED C's and H's that contributes very little to chemical reactions.

Front 38

ROH depicts what functional group?

Back 38

Alcohols.

Front 39

True or False: Rod-shaped molecules have more surface area than spherical molecules, so their boiling points are slightly higher.

Back 39

True.

Front 40

What functional group is RH?

Back 40

Anything with RH is not considered to have a functional group. These are known as "alkanes"

Front 41

Name the functional group (in blue).

Back 41

The carbon/carbon double bond makes this an "alkene".

Front 42

Name the functional group (in blue).

Back 42

The carbon/halogen bond makes this an "alkyl halide".

Front 43

The ___________ is the lowest-energy orbital.

Back 43

The 1s orbital is the lowest-energy orbital.

Front 44

What is a "node" in terms of describing orbitals?

Back 44

A region where the value of the wave function equals zero. (Indicating that electrons spend no time there)

Front 45

Orbitals with the same energy are termed _____________.

Back 45

Degenerate.

Front 46

What is the "Pauli Exclusion Principle"?

Back 46

The Pauli Exclusion Principle states that no 2 electrons can have all four quantum numbers the same.

Front 47

What is "Hund's Rule"?

Back 47

Every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.

Front 48

True or False: The 1s orbital must be full before electrons begin to fill the p orbitals.

Back 48

True. Subshell 2 is the lowest energy subshell with p orbitals. Subshell 1 must fill up before electrons begin to fill 2s and 2p orbitals.

Front 49

The _____________ states that no 2 electrons can have all four quantum numbers the same.

Back 49

Pauli Exclusion Principle

Front 50

True or False: The s orbitals must be full before electrons begin to occupy p orbitals, and p must fill up before electrons begin to occupy d orbitals.

Back 50

False. Hund's Rule states that orbitals in each subshell (subshell 1, subshell 2, subshell 3, etc) get one electron before the other degenerate orbitals fill up. (A full orbital having 2 electrons).