P3- Particle model of matter

What is density?

Measure of mass packed into a given volume

What can the particle model be used to explain?

• Different states of matter

• Differences in density

What does the phrase mass is conserved mean

Number of particles don’t change.

What is the arrangement of a solid?

Strong forces hold particles close together in a fixed regular position

What is the arrangement of a liquid?

Weaker forces but the particles move past eachother at low speeds (allows liquids to flow) in irregular arrangements

What is the arrangement of a gas?

No force of attraction so particle move freely in random directions.

Describe the energy in each state of matter

• Solid- Not much energy, particles vibrate around fixed points.

• Liquid- Move in random directions at low speeds.

• Gas- Even more energy they move in random directions at higher speeds.

Describe density in each state of matter

• Solid- Highest

• Liquid- Slighty less

• Gas- Much less

What is internal energy?

Energy stored its particles, it is also the total kinetic energy and potential energy of all particles

Why is temperature not raised when a substance is melting or boiling?

Energy breaks intermolecular bonds (changing state) instead of raising temperature

Why would internal energy decrease?

When a substance is condensing or freezing they relase energy so internal energy decreases, temperature doesn’t go down till the change of state.

What happens when a substance is heated enough to change state?

Energy breaks bonds between particles increasing potential energy.

What happens when a substance is cooled enough to change state?

Reduces kinetic energy, bonds form between particles reducing potential energy

Are chnages of state physical or chemical?

Changes of state are physical changes which differ from chemical changes because the material recovers its original properties if the change is reversed.