Chapter 8: Covalenet Bonding and Molecular Gemetry

What is a nonpolar covalent bond?

A bond where two atoms share electrons equally. Example

Domains and Angle of LINEAR

2 electron domains, 180 degrees

What is a polar covalent bond?

A bond where two atoms share electrons unequally due to differences in electronegativity. Example

Domains and Angle of TRIGONAL PLANAR

3 electron domains, 120

What is the octet rule?

Atoms tend to gain, lose, or share electrons to achieve a full outer shell of 8 valence electrons.

Domains and Angle of BENT (1 lone pair)

2 electron domains, 118 degrees

What are three properties of covalent compounds?

1. Low melting/boiling points.

2. Poor conductors of electricity.

3. Often soluble in nonpolar solvents

Domains and angle of TETRAHEDRAL

4 electron domains, 109.5 degrees

Domains and angle of TRIGONAL PYRAMIDAL (1 lone pair)

4 electron domains, <109.5 degrees

What are the three steps in drawing Lewis Dot Structures?

• Count total valence electrons.

• Place the least electronegative atom in the center.

• Form bonds and distribute remaining electrons to satisfy the octet rule.

What is VSEPR theory?

The Valence Shell Electron Pair Repulsion (VSEPR) theory states that electron pairs repel each other, determining molecular geometry based on maximum separation.

What is an expanded octet? Give an example.

When the central atom has more than 8 valence electrons. Examples: SF₆ (sulfur hexafluoride), PCl₅ (phosphorus pentachloride)

What is a dipole? Which type of bond creates a dipole?

A separation of charges in a bond, with one end partially positive (δ⁺) and the other partially negative (δ⁻). Polar covalent bonds create dipoles.

How does electronegativity help determine charge distribution in a polar bond?

The more electronegative atom pulls electrons closer, becoming partially negative (δ⁻), while the less electronegative atom becomes partially positive (δ⁺).

What is the difference between intermolecular forces and covalent bonds?

• Covalent bonds are strong forces within a molecule.

• Intermolecular forces are weak attractions between molecules (e.g., hydrogen bonding, dipole-dipole, London dispersion).

Describe the four types of intermolecular forces.

1. Van der Waals Forces: Weak attractions from temporary dipoles.

2. London Dispersion Forces: Induced dipoles in all molecules.

3. Dipole-Dipole Interactions: Between polar molecules.

4. Hydrogen Bonds: Strong interactions between H and N, O, or F.

Name three differences between ionic and covalent compounds.

1. Ionic compounds have high melting points; covalent compounds have low melting points.

2. Ionic compounds conduct electricity when dissolved; covalent compounds do not.

3. Ionic bonds involve electron transfer; covalent bonds involve electron sharing.