Ch. 3: Intro to Organic Compounds

Question 1

What are alkanes and their general molecular formula?

Answer 1

Alkanes are hydrocarbons that contain only single bonds. Their general molecular formula is CnH2n+2.

Question 2

What are constitutional isomers?

Answer 2

Constitutional isomers have the same molecular formula, but their atoms are linked differently.

Question 3

What are some general rules for naming hydrocarbons with substituents and/or functional groups?

Answer 3

When there is only a substituent, the substituent gets the lower of the possible numbers.
When there is only a functional group suffix, the functional group suffix gets the lower of the possible numbers.
When there is both a functional group suffix and a substituent, the functional group suffix gets the lower of the possible numbers.

Question 4

What is a functional group?

Answer 4

A functional group is a center of reactivity in a molecule.

Question 5

How are alkyl halides, ethers, alcohols, and amines named?

Answer 5

Alkyl halides and ethers are named as substituted alkanes. Alcohols and amines are named using a functional group suffix.

Question 6

Systematic names vs. common names

Answer 6

Systematic names can contain numbers while common names never do.

Question 7

What does it mean if alkyl halides or alcohols are primary, secondary, or tertiary?

Answer 7

Alkyl halides or alcohols are primary, secondary, or tertiary depending on whether the X (halogen) or OH group is attached to a primary, secondary, or tertiary carbon, respectively.

Question 8

What does it mean if amines are primary, secondary, or tertiary?

Answer 8

Amines are primary, secondary, or tertiary depending on the number of alkyl groups attached to the nitrogen.

Question 9

Compounds with 4 alkyl groups attached to a nitrogen are called _____________________.

Answer 9

quarternary ammonium salts

Question 10

The oxygen of an alcohol or an ether has the same geometry as (1) ____________ .
The nitrogen of an amine has the same geometry as the (2) _____________ .

Answer 10

(1) oxygen of water

(2) nitrogen of ammonia

Question 11

Rank the following attractive forces between molecules from weakest to strongest (hint: there are 3 types to mention).

Bonus: What is the relationship between the boiling point of a compound and the type of attractive forces involved?

Answer 11

Ranking from weakest to strongest: van der Waals forces, dipole-dipole interactions, and hydrogen bonds.

Bonus: The boiling point of a compound increases as the attractive forces between its molecules strengthen.

Question 12

What is a hydrogen bond?

Answer 12

A hydrogen bond is an interaction between a hydrogen attached to an O, N, or F and a lone pair of another O, N, or F.

Question 13

How does boiling point relate to molecular weight? To branching?

Answer 13

The boiling point increases with increasing molecular weight. Branching lowers the boiling point.

Question 14

Define polarizability.

Answer 14

Polarizability indicates the ease with which an electron cloud can be distorted. Larger atoms are more polarizable.

Question 15

Explain what “like dissolves like” means.

Answer 15

“Like dissolves like” means that polar compounds dissolve in polar solvents and nonpolar compounds dissolve in nonpolar solvents.

Question 16

When faced with a solution of water, how many carbons can the oxygen of an alcohol or ether drag?

Answer 16

The oxygen of an alcohol or ether can drag 3 or 4 carbons into solution in water.

Question 17

What are conformers?

Answer 17

Conformers are different combinations of the same compound. They cannot be separated.

Question 18

Staggered conformer vs. eclipsed conformer

Answer 18

A staggered conformer is more stable than an eclipsed conformer because of hyperconjugation.

Question 19

Anti conformer vs. gauche conformer

Answer 19

The anti conformer is more stable than a gauche conformer because of steric train, which is repulsion between the electron clouds of atoms or groups.

Question 20

5- and 6 membered rings vs. 3- and 4-membered rings

Answer 20

5- and 6-membered rings are more stabe than 3- and 4-membered rings because of the angle strain that results when bond angles deviate markedly from the ideal bond angle of 109.5 degrees.

Question 21

What is a ring flip?

Answer 21

Ring flip occurs when cyclohexane rapidly interconverts between two stable chair conformers.

Question 22

Equatorial substituent vs. axial substituent

Answer 22

Equatorial substituents have less steric strain and thus are more stable than axial substituents.

Question 23

What causes axial substituents to be less favorable and stable?

Answer 23

Axial substituents experience 1,3-diaxial interactions.

Question 24

Cis isomer vs. trans isomer

Answer 24

Cis isomer has its two substituents on the same side of the ring while a trans isomer has its substituents on opposite sides of the ring.

Question 25

For a disubstituted cyclohexane, what makes for a more stable conformer?

Answer 25

The more stable conformer of a disubstituted cyclohexane has its larger substituent on an equatorial bond.