Unit 2 Practice: Easy

Answer: Ionic bonding

Explanation: Na is a metal and Cl is a nonmetal. Na tends to lose an electron to form Na⁺, while Cl tends to gain an electron to form Cl⁻. The attraction between these oppositely charged ions creates ionic bonding.

Answer: Covalent bonding

Explanation: Carbon and oxygen are both nonmetals. Instead of forming a lattice of ions, they share electrons through covalent bonds.

Answer: Metallic bonding

Explanation: Metal atoms are held together by attraction between positive metal cores and delocalized valence electrons. These mobile electrons also help explain why copper conducts electricity.

Answer: 2 electrons

Explanation: A single covalent bond contains one shared electron pair.

Therefore:

1 bond = 2 shared electrons

Answer: 4 electrons

Explanation: A double bond contains two shared electron pairs.

Therefore:

2 pairs × 2 electrons = 4 electrons

Answer: C=C

Explanation: The C=C bond has a higher bond order.

For the same pair of elements:

higher bond order → stronger bond → shorter bond

Answer: Triple bond

Explanation: A triple bond has a higher bond order and more electron density between the nuclei.

For comparable atoms:

triple > double > single

in bond strength.

Answer:

H—O—H

Oxygen also has two lone pairs.

Explanation: Water has 8 total valence electrons:

2 from the two H atoms and 6 from O.

Two O—H bonds use four electrons. The remaining four electrons form two lone pairs on oxygen.

Answer: 2 lone pairs

Explanation: Oxygen has six valence electrons. After forming two O—H bonds, four nonbonding electrons remain.

Four electrons make:

2 lone pairs

Answer: Linear

Explanation: Carbon has two electron groups:

O=C=O

Each double bond counts as one electron group.

Two electron groups arrange themselves 180° apart.

Answer: Tetrahedral

Explanation: Carbon has four bonding groups and no lone pairs.

VSEPR places the four groups as far apart as possible, producing a tetrahedral shape.

Answer: Trigonal pyramidal

Explanation: Nitrogen has four electron groups:

3 bonding groups 1 lone pair

The electron geometry is tetrahedral, but molecular geometry considers only atom positions.

Therefore NH₃ is trigonal pyramidal.

Answer: Bent

Explanation: Oxygen has:

2 bonding groups 2 lone pairs

There are four total electron groups, giving tetrahedral electron geometry.

Looking only at the atoms gives a bent molecular geometry.

Answer: 109.5°

Explanation: CH₄ has tetrahedral geometry.

The ideal tetrahedral bond angle is approximately:

109.5°

Answer: sp³

Explanation: The basic AP Chemistry relationship is:

4 electron groups → tetrahedral electron geometry → sp³

Answer: sp²

Explanation:

3 electron groups → trigonal planar electron geometry → sp²

Answer: sp

Explanation:

2 electron groups → linear electron geometry → sp

Answer: 1 sigma bond

Explanation: A double bond contains:

1 sigma bond + 1 pi bond

The sigma bond forms from head-on orbital overlap.

Answer: 2 pi bonds

Explanation: A triple bond contains:

1 sigma + 2 pi

Every multiple bond still contains only one sigma bond between the two atoms.

Answer: 0

Work:

Use:

FC = valence electrons − dots − lines

FC = 5 − 2 − 3

FC = 0

Explanation: “Dots” represent nonbonding electrons, while “lines” represent bonds.