Introduction to Chemistry and Key Concepts

Chemistry

The study of how particles interact and change.

Law of Conservation of Mass

Matter is not created or destroyed in a chemical reaction.

Gases

Pressure, volume, and temperature affect each other.

Molecular Motion

More movement = more energy.

Phases of Matter

Solid, liquid, gas, and plasma have different properties.

Solutions

Mixtures of substances.

Solubility

How well something dissolves.

Acids

Have extra H⁺ ions.

Bases

Have extra OH⁻ ions.

Balanced Equations

Same number of atoms on both sides.

Synthesis

Two things combine → A + B → AB

Decomposition

One thing breaks down → AB → A + B

Single Replacement

One element swaps → A + BC → AC + B

Double Replacement

Two elements swap → AB + CD → AD + CB

Boyle's Law

When temperature is constant, as pressure increases, volume decreases.

Charles's Law

When pressure is constant, as temperature increases, volume increases.

Gay-Lussac's Law

When volume is constant, as temperature increases, pressure increases.

Solid

Fixed shape, atoms close together.

Liquid

No fixed shape, definite volume.

Gas

No fixed shape or volume, expands to fill space.

Plasma

Superheated gas with free electrons (e.g., the Sun).

Density

Formula: Density = mass ÷ volume

Denser materials

Have more mass in the same space.

Physical Properties

Can be observed without changing (e.g., color, melting point).

Chemical Properties

Describe how a substance reacts (e.g., flammability).

Mixture

Two or more substances combined.

Solution

A well-mixed mixture of solute (what dissolves) and solvent (what does the dissolving).

Saturation

Saturated: Holds the maximum solute.

Unsaturated

Can hold more solute.

Supersaturated

Holds more solute than normal.

Factors Affecting Solubility

Stirring → Helps dissolve faster.

Smaller particles

Dissolve faster.

Temperature effect

Solids: Dissolve better in hot liquids. Gases: Dissolve better in cold liquids.

Electrolytes

Substances that conduct electricity when dissolved.

Strong Electrolytes

Fully dissolve (e.g., salt, acids).

Weak Electrolytes

Partially dissolve (e.g., vinegar, ammonia).

Nonelectrolytes

Do not conduct electricity (e.g., sugar).