Unit 2 States of Matter

Kinetic Theory of Matter

All matter is made up of molecules that are in constant motion.

States of Matter

The physical forms in which matter can exist.

Endothermic Change

A process where a substance gains energy from its surroundings, causing particles to speed up.

Exothermic Change

A process where a substance loses energy to its surroundings, causing particles to slow down.

Freezing

The process where particles of a liquid lose energy, slow down, and turn into a solid.

Melting

The process where particles of a solid gain energy, speed up, and turn into a liquid.

Boiling

The process where particles of a liquid gain energy, speed up and turn into a gas at the boiling point.

Evaporation

A gradual process that occurs only at the surface of a liquid, at temperatures lower than the boiling point.

Condensation

The process where particles of a gas lose energy, slow down, and change into a liquid.

Sublimation

The process where particles of a solid gain energy, skip the liquid state, and go directly into the gas state.

Deposition

The process where particles of a gas lose energy, skip the liquid state, and go directly into the solid state.

Temperature during a change in state

Remains constant during a change in state.

Conservation of Mass

The number and size of the particles does NOT change during a change in state.

Boiling point decrease at higher elevations

Less air pressure makes it easier for water to change from liquid to gas, requiring less energy to boil.

Boiling point increase in a pressure cooker

Increased pressure makes it harder for water to change from liquid to gas, requiring more energy to boil.

Solid

A state of matter characterized by definite shape and volume, where particles are closely packed together.

Liquid

A state of matter with a definite volume but no definite shape, allowing particles to flow past one another.

Gas

A state of matter with no definite shape or volume, where particles are far apart and move freely.

Kinetic Theory of Matter

A theory that explains the behavior of matter based on the idea that particles are always in motion.

Melting

The process of changing a solid into a liquid by adding heat.

Freezing

The process of changing a liquid into a solid by removing heat.

Boiling

The rapid vaporization of a liquid when it reaches its boiling point.

Evaporation

The process by which liquid changes into gas at temperatures below its boiling point.

Condensation

The change of state from gas to liquid, often seen when dew forms on grass.

Sublimation

The process where a solid changes directly into gas without becoming a liquid first.

Deposition

The process where a gas changes directly into a solid without becoming a liquid first.

Endothermic process

A process that absorbs heat from the environment, resulting in a temperature decrease.

Exothermic process

A process that releases heat into the environment, resulting in a temperature increase.

Physical change

A change in a substance that does not alter its chemical composition, such as melting or freezing.

Chemical change

A change that results in the formation of new chemical substances, such as rusting or burning.