Chemistry II: Intermolecular Forces

Vocabulary flashcards covering chemical bonds versus intermolecular forces, dipole types, molecular geometry, and physical properties based on the Chemistry II study notes.

Chemical bonds

Forces that hold atoms together within a molecule or compound.

Intermolecular forces (IMFs)

Attractions between separate molecules.

Covalent bonds

Bonds that form when atoms share electrons.

Ionic bonds

Attractions between oppositely charged ions.

Dispersion forces (LDFs)

Intermolecular forces caused by temporary, uneven distributions of electrons that induce dipoles in neighbouring particles; present in all atoms and molecules and usually the weakest type for similarly sized particles.

Dipole dipole forces

Attractions between the slightly positive end of one polar molecule and the slighty negative end of another, depending on molecules having permanent dipoles.

Hydrogen bonding

A particularly strong type of dipole–dipole attraction where hydrogen is covalently bonded directly to nitrogen (N), oxygen (O), or fluorine (F), attracting the partially positive hydrogen to N, O, or F on a neighbouring molecule.

Permanent dipole

A lasting uneven distribution of charge in a polar molecule.

Temporary dipole

A brief uneven distribution of electrons caused by electron motion.

Polar molecule

A molecule that has an uneven charge distribution and a net dipole.

Boiling

A physical process that overcomes intermolecular attractions between molecules rather than the covalent bonds inside molecules.

Water molecular geometry

A bent shape with a bond angle of approximately $104.5^\natural$, which prevents its $O-H$ bond dipoles from cancelling out and makes the molecule polar.

Carbon dioxide ($CO_2$)

A nonpolar molecule whose linear molecular shape causes its bond dipoles to cancel each other out.

Sulfur dioxide ($SO_2$)

A bent, polar molecule experiencing dispersion and dipole–dipole forces that does not form hydrogen bonds with itself because it has no hydrogen bonded to N, O, or F.

Noble gases (e.g., Helium)

Individual atoms that experience dispersion forces resulting from temporary dipoles causing weak attractions between atoms.