Chapter 11 & 12 — AP Chemistry

What determines a substances state? ( solid, liquid, gas )

The balance between kinetic energy (KE) and intermolecular forces (IMFs)

As temperature decreases, what happens to particle motion and spacing?

Particles move slower and get closer together

Which state is compressible and flows easily?

Gas

How do IMFs compare to covalent or ionic bonds?

IMFs are much weaker than intramolecular bonds.

What physical properties depend on IMFs?

Boiling point, melting point, viscosity surface tension, and capillary action

List IMF’s from strongest ti weakest

Ion-Dipole —> Dipole-Dipole —> Hydrogen Bond —> Dipole-Induced Dipole —> Dispersion (LDF)

What increases ion-dipole strength?

Smaller ion radius, larger ion charge, and stronger molecular dipole

What type of molecules experience dipole-dipole forces?

Polar molecules with partial positive and negative ends

How does molecular polarity affect boiling point?

More polar = higher boiling point

What elements form hydrogen bonds?

Hydrogen bonded to F, O, or N

Why are Hydrogen bonds strong?

Very polar bonds + small atoms + concentrated partial charges

Give examples of hydrogen bonding

H2O, NH3, HF, DNA base pairing

When do dipole-induced dipole forces occur?

Between a polar molecule and a Nonpolar molecule whose electrons could is distorted

What increases dipole-induced dipole attraction?

Larger dipole strength and more polarization electron cloud.

What causes dispersion forces?

Temporary fluctuations in electron distribution = temporary dipoles

Do all molecules have dispersion forces?

Yes

What factors strength dispersion forces?

More electrons, higher molar mass, larger or elongated shape

What is polarizability?

How easily an atoms electron cloud can be distorted

What is viscosity?

Resistance to flow; increases with stronger IMFs, decreases with high temperature

What is surface tension?

Inward force at a liquids surface causes by cohesive IMFs

Define cohesion and adhesion

Cohesion is attraction between same molecules

Adhesion is attraction to a surface