Fundamental Properties and States of Matter

States of Matter

Properties of Gases: A gas tends to occupy the entire volume of the container; the mass of the gas remains the same even if you modify the size of the container. Gases are very sensitive to temperature changes.

Properties of Fluids and Liquids

Liquids have a constant volume. The liquid adapts to the shape of the container. They swell much less than gases.

Properties of Solids

Solids have a fixed volume and a constant shape. They swell even less than liquids.

Phase Changes and Transitions

• Evaporation: The change from liquid to gas occurs at the surface of the liquid.
• Boiling: In appropriate circumstances, a change of state can occur within the liquid; then, the formed gas bubbles rise to the surface and escape.

Common State Transitions

• Solid to Liquid: Fusion
• Liquid to Gas/Steam: Vaporization
• Solid to Gas/Steam: Sublimation
• Gas/Steam to Solid: Reverse Sublimation
• Gas/Steam to Liquid: Condensation

Pure Substances and Elements

Pure Substances: These are substances that have qualities and characteristics that differentiate them from others. Pure substances that can be decomposed into simpler ones are called compounds.

The elements are pure substances that cannot be decomposed into simpler ones.

Hydrogen and Helium

Hydrogen: It is the most abundant chemical element in the universe. It is a gas at room temperature and is found in large numbers in the stars.

Helium: It is a colorless, odorless, and tasteless gas.

Atomic Structure and Particle Motion

Atoms: Matter is made up of particles. Everything we see, smell, and touch is made up of particles, which may be atoms or molecules.

Liquid and Solid Structures

• Liquid Structures: Particle attraction forces exist; they prevent the particles from being separated too much. The particle motion is more limited but still allows movement.
• Solid Structures: These are formed by particles that are very close together; the attractive forces are stronger than in liquids. The particles are not free from a fixed position.

Mixtures and Solutions

Mixing Concept: In most cases in nature, we find mixtures. A substance within a mixture retains its identity and its own properties; the substances in the mixture are called components.

• Homogeneous Mixtures: The components do not differ from one another.
• Heterogeneous Mixtures: The components differ and can be seen with the naked eye.

Solubility and Temperature

A solution is a homogeneous mixture of a solvent and a solute. In a solution, both the solute and the solvent can be liquid, solid, or gas.

Solubility: The value of solubility depends on the solvent and the temperature. For the same solvent, solubility varies: the solubility of solids increases with increasing temperature, while the solubility of gases decreases with increasing temperature.