states of matter

chemistry

what are the three states of matter

solid, liquid, gas

how are particles arranged in a solid

Tightly packed in a fixed, regular arrangement; they vibrate around fixed positions

how are particles arranged in a liquid

Close together but not in a fixed pattern; they can move around each other

how are particles arranged in a gas

Far apart and move freely and randomly in all directions

what happens to the energy of particles as temperature increases

Particles gain kinetic energy and move faster

what happens during melting in terms of particle movement

Particles gain enough energy to overcome some of their forces of attraction and begin to move around each other

What happens during freezing

Particles lose energy and move more slowly, becoming fixed in place in a regular structure

What happens during boiling or evaporation

Particles gain enough energy to completely overcome forces of attraction and move apart to form a gas

What happens during condensation

Gas particles lose energy and move closer together to form a liquid

What happens during sublimation

Particles change directly from a solid to a gas without becoming a liquid

What are the forces like between particles in solids, liquids, and gases

Strong in solids, weaker in liquids, and very weak (almost none) in gases

How does diffusion occur in gases

Gas particles move randomly and spread out to fill the available space

Why does diffusion happen more slowly in liquids than in gases

Particles are closer together and move less freely than in gases

How does temperature affect the rate of diffusion

Higher temperature increases particle energy and speed, so diffusion happens faster

How can you describe the changes of state on a heating curve

Flat sections show changes of state (melting or boiling), where energy is used to break forces between particles instead of raising temperature

What is the difference between evaporation and boiling

Evaporation occurs at any temperature from the surface; boiling happens throughout the liquid at a fixed temperature (boiling point)

What is meant by the term "intermolecular forces"

The attractive forces between particles (molecules or atoms) that hold them together

Why do solids have a fixed shape but gases do not

Because their particles are held in fixed positions by strong forces; gases do not because their particles move freely

Why do gases expand to fill their container

Because particles move rapidly in all directions with little attraction between them

What happens to the pressure of a gas if its temperature increases (at constant volume)

Increasing temperature increases particle speed and collision frequency, so pressure increases (if volume stays constant)