changes of state and particle model

• What are the three common states of matter?

  Solids, liquids, and gases
• How are particles arranged in a solid?

  Very close together in a regular pattern
• What kind of movement do particles in a solid exhibit?

  They vibrate but do not move
• How are particles arranged in a liquid?

  Close together, but not in a pattern
• What is the movement of particles in a liquid?

  Particles can move around each other
• How are particles arranged in a gas?

  Very far apart and no pattern
• How do particles move in a gas?

  They are moving very rapidly
• What does the density of a material tell us?

  The mass for a given volume
• What is the relative density of a brick?

  High density
• What is the relative density of a polystyrene block?

  Low density
• What is the unit of density?

  Kilograms per meter cubed
• Why do solids usually have a high density?

  Particles are closely packed together
• Why do liquids usually have a high density?

  Particles are close together
• Why do gases have a low density?

  Particles are very far apart
• Why does polystyrene have a low density despite being a solid?

  Due to its open structure
• What causes polystyrene to have a smaller mass for its volume?

  Air spaces
• Why are solids extremely hard to compress?

  Particles packed in a regular pattern with almost no spaces
• What two properties do solids have, as a result of particle behaviour?

  Fixed shape and they cannot flow
• What behavior do solid particles exhibit?

  They can vibrate
• Why are liquids extremely hard to compress?

  Particles are close together with not many spaces
• What two properties do liquids have, as a result of particle behaviour?

  Take container shape and flow from place to place
• Why can particles in a liquid move?

  Due to overcoming intermolecular forces
• Why are gases extremely easy to compress?

  The particles and gases are widely spaced
• What behavior do gas particles exhibit that causes them to spread out?

  Move quickly and randomly
• What is the name of the process where a solid changes into a liquid?

  Melting
• At what point does melting occur?

  At the melting point
• How does the kinetic energy of particles in a liquid compare to that of a solid?

  Liquids have more kinetic energy
• What must be input to convert a solid into a liquid?

  Energy
• What is the role of energy during melting?

  Break the forces of attraction
• What is the relationship between the strength of attraction and melting point?

  Stronger forces, higher melting point
• Why does candle wax have a relatively low melting point?

  Weak forces of attraction
• Why does sodium chloride have a very high melting point?

  Very strong forces of attraction
• What is the name of the process where a liquid changes into a solid?

  Freezing
• At what temperature does freezing occur?

  The melting point
• What is the name of the process where a liquid changes into a gas?

  Boiling
• At what point does boiling take place?

  At the boiling point
• What leads to a high boiling point?

  Strong forces of attraction
• What is the name of the process where a gas changes back into a liquid?

  Condensing
• At what point does condensing take place?

  At the boiling point
• What does the simple particle model assume about the shape of particles?

  All particles are solid spheres