Organic Chemistry Chapter 2: Molecular Dipoles, Intermolecular Forces, and Solubility

What causes dipole moments in molecules?

Differences in electronegativity.

What factors influence dipole moments?

The amount of charge and distance of separation.

In what unit are dipole moments measured?

Debyes (D).

What is the molecular dipole moment?

The vector sum of the bond dipole moments.

What contributes to the molecular dipole moment?

Bond polarity, bond angles, and lone pairs of electrons.

What are intermolecular forces?

Strength of attractions between molecules that influence melting point, boiling point, and solubility.

Name the three classifications of attractive forces.

Dipole-dipole forces, London dispersion forces, and hydrogen bonding.

What occurs during dipole-dipole interactions?

Attractive or repulsive interactions between the positive and negative ends of polar molecules.

What are London dispersion forces?

Temporary dipole moments that can induce dipole moments in nearby molecules.

Which type of molecules primarily experience London dispersion forces?

Nonpolar molecules.

How does branching affect boiling points?

Increased branching decreases surface area and boiling point.

What is required for hydrogen bonding to occur?

Molecules must have N—H or O—H groups.

Why do alcohols have higher boiling points than amines?

O—H is more polar than N—H, leading to stronger hydrogen bonding in alcohols.

What principle explains solubility?

Like dissolves like.

What happens when a polar solute is placed in a polar solvent?

The polar solute dissolves due to similar intermolecular forces.

Why won't a polar solute dissolve in a nonpolar solvent?

The solvent cannot break apart the intermolecular interactions of the polar solute.

What occurs when a nonpolar solute is placed in a nonpolar solvent?

The nonpolar solute dissolves due to weak intermolecular attractions being overcome.

What are the three broad classes of compounds based on functional groups?

Hydrocarbons, compounds containing oxygen, and compounds containing nitrogen.