Properties of Substances and Mixtures (AP Exams) — Complete Study Guide

London Dispersion Forces (LDFs)

The weakest type of IMF exists between all atoms and molecules.

Dipole-Induced Dipole Interactions

Occur when a polar molecule induces a dipole in a nonpolar molecule by distorting its electron cloud.

Dipole–Dipole Interactions

Occur between two polar molecules with permanent dipoles. Molecules align positive end to negative end.

Ion–Dipole Interactions

Occur between an ion and a polar molecule.

Molecular Dipole Moment

A measure of net polarity in a molecule; vector sum of all bond dipoles.

Hydrogen Bonding

Special case of strong dipole–dipole interaction. Occurs when H is bonded to N, O, or F and attracted to a lone pair on another N, O, or F atom.

Solids

They have strong particle attractions, fixed shape, and volume.

Liquids

They have fixed volume, variable shape, and moderate IMFs.

Ionic Solids

Have high melting point, hard, and brittle

Covalent Network Solids

Atoms held by covalent bonds in a continuous network. They are very hard, have high melting points, and poor conductors.

Molecular Solids

Made of discrete molecules held by IMFs (not covalent or ionic bonds). They have low melting points, soft, and poor electrical conductors.

Metallic Solids

Consist of metal cations surrounded by a sea of delocalized electrons. They are malleable, ductile, and Electrically/Thermally Conductive.

Unit cells

They are the smallest repeating unit.

PV = nRT

What is the formula used for the Ideal Gas Law?

Boyle’s Law

Which law forms this type of graphical presentation?

Charles’ Law

Which law forms this type of graphical presentation?

Avogadro’s Law

Which law forms this type of graphical presentation?

Kinetic Molecular Theory (KMT)

Gas particles are in constant random motion. Volume of individual molecules ≈ negligible. Collisions are elastic (no energy loss). Average kinetic energy ∝ temperature (Kelvin). Explains pressure as particle collisions with container walls.

The Maxwell–Boltzmann Distribution

Describes range of molecular speeds in a gas sample. At higher temperatures: Distribution broadens and average kinetic energy increases. Lighter molecules move faster on average.

Non-Ideal Behavior of Gases

Deviate from ideal gas law at high pressures or low temperatures. Attractive forces lower pressure; finite volume reduces free space.

Molarity

Fill in the blank

________ (M): M = moles solute / liters solution.

Molality

Fill in the blank

________ (m): m = moles solute / kg solvent.

Heterogenous mixtures

Fill in the blank

Homogeneous mixtures: uniform composition (solutions).

______________________: non-uniform, distinct phases (suspensions, emulsions).

The Electromagnetic Spectrum

It moves from shorter wavelength to higher energy.

Gamma

Fill in the blank

Radio → Microwave → Infrared → Visible → UV → X-ray → _______.

Photoelectric effect

Light of sufficient energy ejects electrons from metal surface.

nonpolar

If polar dissolves polar, a nonpolar dissolves?

ion–dipole

Ionic compounds dissolve via these type of interactions.

titrations

Fill in the blank

Molarity is important for __________ and reaction concentration control.

dipole–dipole or hydrogen

Molecular solutes dissolve via these types of bonding.

Beer–Lambert Law

Higher concentration → higher absorbance (linear relationship).

Heterogenous

What type of mixture is sand in water?

Homogeneous

What type of mixture is air?