States of Matter: Solid: Particles are packed closely together, vibrating in place. Solids have a fixed volume & shape. Liquid: The attractive forces between particles are weaker than in a solid. Liquids have a definite volume, but not a definite shape.

States of Matter: Gas: Particles are much farther apart than in liquid or a solid, the attraction forces between them are weak. Gases do not have definite shape or volume. Plasma: Is matter consisting of (+) & (-) charged particles. Do not have a definite shape or volume. Is the most common state of matter in the universe (The stars, including the Sun contain plasma).

Phase Changes: Melting: Is the process by which the substance changes from solid to liquid. The temperature at which this process occurs is called melting point. Freezing: Is the process by which the substance changes from liquid to solid. The temperature at which this process occurs is called freezing point.

Heating curve of water.

Phase Changes: Boiling: Is the process by which the substance changes from liquid to gas. The temperature at which this process occurs is called boiling point. Condensation: Is the process by which the substance changes from gas to liquid.

Heating curve of water.

Phase Changes: Sublimation: Is the process by which the substance changes from solid to gas. Deposition: Is the process by which the substance changes from gas to solid.

Melting Boiling Sublimation Phase Changes: Melting Boiling Sublimation Absorb energy (endothermic processes) Freezing Condensation Deposition Release energy (exothermic processes)

Heating curve of water.

Vaporization The conversion of a liquid to a gas or vapor is called vaporization (evaporation or boiling): 1) Evaporation: When this conversion occurs at the surface of a liquid at room temperature. 2) Boiling occurs in the entire mass of a liquid, this process require more thermal energy than evaporation.

evaporation is a cooling process. As evaporation occurs, the particles with the highest kinetic energy tend to escape first. As evaporation takes place, the liquid’s temperature decreases because the particles take the energy from its surrounding to become to gas, then evaporation is a cooling process.

You can observe the effects of evaporative cooling on hot days. When you perspire, water molecules in your perspiration absorb heat from your body and evaporate from the skin’s surface. This evaporation leaves the remaining perspiration cooler. * The perspiration that remains cools you further by absorbing more body heat.