AP Chemical Bonding and Molecular Structure 2

Question 1

Using VSEPR theory, what is the molecular geometry and approximate bond angle in SF₄?

Accepted Answer

Seesaw (sawhorse) geometry, ~102° and ~173°

Answer

Tetrahedral geometry, 109.5°

Answer

Trigonal pyramidal geometry, ~107°

Answer

Square planar geometry, 90°

Question 2

Which of the following molecules has a dipole moment of zero?

Accepted Answer

CO₂

Answer

H₂O

Answer

NH₃

Answer

SO₂

Question 3

What is the hybridization of the central carbon in ketene, H₂C=C=O?

Accepted Answer

The terminal CH₂ carbon is sp² and the central carbon bonded to O is sp

Answer

Both carbons are sp²

Answer

Both carbons are sp

Answer

The terminal CH₂ is sp³ and the central carbon is sp²

Question 4

In molecular orbital theory, which of the following correctly describes the bond order and magnetic properties of O₂?

Accepted Answer

Bond order = 2, paramagnetic (2 unpaired electrons)

Answer

Bond order = 3, diamagnetic

Answer

Bond order = 2, diamagnetic

Answer

Bond order = 1, paramagnetic

Question 5

Arrange these bonds in order of increasing bond length: C–C single, C=C double, C≡C triple, C–H.

Accepted Answer

C–H < C≡C < C=C < C–C

Answer

C≡C < C=C < C–C < C–H

Answer

C≡C < C–H < C=C < C–C

Answer

C–C < C=C < C≡C < C–H

Question 6

Which of the following best explains why the H–N–H bond angle in NH₃ (~107°) is smaller than the H–C–H bond angle in CH₄ (109.5°)?

Accepted Answer

The lone pair on N exerts greater repulsion on the bonding pairs than a bonding pair would, compressing the H–N–H angles

Answer

N is more electronegative than C, pulling bonding electrons toward it and increasing angles

Answer

NH₃ is a polar molecule while CH₄ is nonpolar, and polarity decreases bond angles

Answer

N–H bonds are shorter than C–H bonds, bringing H atoms closer together