Conformational Analysis

Question 1

Staggered Degree Options

Answer 1

60, 180, 300

Question 2

Eclipsed Degree Options

Answer 2

0, 120, 240

Question 3

Are staggered or eclipsed conformations higher in energy? Why?

Answer 3

Eclipsed bc
(1) e- in eclipsed bonds repel
(2) staggered conformations have stabilizing C-H sigma bonds interactions and empty C-H antibonding orbitals

Question 4

Anti vs. Gauche

Answer 4

Anti conformations feature larger groups 180 degrees apart
Gauche feature larger groups right next to each other

Question 5

What is lower in energy: anti or gauche?

Answer 5

Usually anti bc the larger groups are on opposite ends (farther)

Question 6

Steric Strain

Answer 6

PE of molecules increases due to e- repulsion arising from distance between atoms decreasing

Question 7

Torsional Strain

Answer 7

Repulsion due to atoms being rotated around a sigma bond

Question 8

E vs Z

Answer 8

Z: Priority groups on Zame Zide
E: not

Question 9

What is the chirality of N sp3? Por que?

Answer 9

Achiral bc undergoes inversion very fast & so its enantiomers form a racemic mixture

Question 10

Why are some N’s not chiral even though they have 4 different groups?

Answer 10

Bc the N is conjugated (its LP are used in resonance) and so it is actually sp2 hybridized, which cannot produce chirality

Question 11

How many e- in an antibonding sigma is considered unstable?

Answer 11

2e-

Question 12

What is higher in E, 2p AO or 2s AO?

Answer 12

2p bc it has a node & bc 2s does not have a node, its e- can be closer to the nucleus, making 2s lower in E

Question 13

Does P have a node or nah?

Answer 13

Does have a node

Question 14

Does S have a node or nah?

Answer 14

Nahh no node

Question 15

Node Definition (in wave function)

Answer 15

change from + to - phase

Question 16

Is S radial or angular?

Answer 16

radial

Question 17

Is p radial or angular?

Answer 17

Angular

Question 18

Does constructive interference enhance overlap? 왜?

Answer 18

Nah bc of nuclear repulsion

Question 19

What is stronger, P or sigma bonds? 왜?

Answer 19

P is weaker than sigma bc
(1) Poor overlap in pi (maximum in sigma)
(2) p’s density is located above and below the atoms, while sigma’s e- density is between the atoms

Question 20

Why do atomic orbitals hybridize?

Answer 20

To enhance overlap when forming a bond! :D

Question 21

How many molecular orbital would form from n atomic orbitals?

Answer 21

n (same #!)

Question 22

Nuclear Node vs. Antibonding Node?

Answer 22

Nuclear: AO’s node (ex: 2p)
Antibonding: change in sign between 2 diff. atoms

Question 23

What requires more energy, sigma bond rotation or pi bond rotation?

Answer 23

pi

Question 24

What requires more energy, a pi bond rotation or breaking a pi bond?

Answer 24

Same!

Question 25

What requires more energy, a pi bond rotation or breaking a sigma bond?

Answer 25

pi bond rotation!