AP Chemistry: Chemical Bonding & Molecular Structure 2

Question 1

According to VSEPR theory, what is the molecular geometry of a molecule with two bonding pairs and two lone pairs on the central atom (AX2E2)?

Accepted Answer

Bent

Answer

Two bonding pairs and two lone pairs (AX2E2) give a bent molecular shape, as in water.

Question 2

Which molecule contains a coordinate (dative) covalent bond?

Accepted Answer

NH4+

Answer

In NH4+ the nitrogen lone pair forms a coordinate bond with H+, where both electrons come from nitrogen.

Question 3

What is the hybridization of the carbon atom in a molecule of carbon dioxide (CO2)?

Accepted Answer

sp

Answer

Carbon in CO2 has two electron domains (two double bonds), giving sp hybridization.

Question 4

Which of the following best explains why a water molecule is polar?

Accepted Answer

Its bent shape gives an uneven distribution of charge

Answer

Water's bent geometry prevents the O-H bond dipoles from canceling, producing a net molecular dipole.

Question 5

How many sigma and pi bonds are present in a molecule of nitrogen gas (N2)?

Accepted Answer

1 sigma, 2 pi

Answer

A triple bond consists of one sigma bond and two pi bonds, so N2 has 1 sigma and 2 pi bonds.

AP Practice Test