Molecular Attraction

Forces of Attraction Chapter 12 Section 2

Intramolecular Forces

The attractive forces that hold particles together in ionic, covalent, and metallics bonds are called intramolecular forces.

Intermolecular Forces

Attractive forces between molecules cause some materials to be solids, some to be liquids, and some to be gases at the same temperature.

Multiple Choice

Which are stronger, intramolecular forces or intermolecular forces?

• intramolecular forces

• intermolecular forces

Intermolecular Forces cont.

Dispersion forces are weak forces that result from temporary shifts in density of electrons in electron clouds.

Multiple Choice

Dispersion forces are

• are weak forces that result from a temporary shift of electrons in electron clouds.

• are forces of attraction between permanent charged regions between molecules.

• an attraction between molecules containing a hydrogen atom bonded to a highly electronegative atom.

Intermolecular Forces cont.

Dipole-dipole forces are attractions between oppositely charged regions of polar molecules.

Multiple Choice

Dipole-dipole forces are

• are weak forces that result from a temporary shift of electrons in electron clouds.

• are forces of attraction between permanent charged regions between molecules.

• an attraction between molecules containing a hydrogen atom bonded to a highly electronegative atom.

Intermolecular Forces cont.

Hydrogen bonds are special dipole-dipole attractions that occur between molecules that contain a hydrogen atom bonded to a small, highly electronegative atom with at least one lone pair of electrons, typically fluorine, oxygen, or nitrogen.

Multiple Choice

Hydrogen bonds are

• are weak forces that result from a temporary shift of electrons in electron clouds.

• are forces of attraction between permanent charged regions between molecules.

• an attraction between molecules containing a hydrogen atom bonded to a highly electronegative atom.

Intermolecular Forces cont.

• Hydrogen bonds explain why water is a liquid at room temperature while compounds of comparable mass are gases.

• Methane is nonpolar, so relatively weak dispersion forces holding the molecule together.

Intermolecular Forces cont.

• Ammonia and Water both form hydrogen bonds but oxygen is more electronegative than nitrogen making O-H bonds more polar and thus stronger

End