SC1 States Of Matter

Question 1

SC1a
1) What are the three states of matter?
2) What is the particle model?
3) Are state changes chemical or physical changes?
4) Explain the forces of attraction in states of matter.

Answer 1

1) The three states of matter are solid, liquid and gas.
2) The particle model explains arrangement, movement and energy stored in its particles during state changes.
3) State changes are physical changes. They can be reversed, and the chemical properties of the substance do not change.
4) Particles are attracted to each other by weak forces of attraction. There are many of these in a solid. These attractive forces are overcome during melting, evaporating and boiling (when a substance is evaporating as fast as it can). Attractive forces form during condensing and freezing.

Question 2

SC1a
1) What is the particle arrangement in a solid?
2) What is the particle arrangement in a liquid?
3) What is the particle arrangement in a gas?

Answer 2

1) The particle arrangement in a solid is regular and close together (touching), and they vibrate in fixed positions.
2) The particle arrangement in a liquid is random and close together (touching). The particles move around each other randomly.
3) The particle arrangement in a gas is random and far apart. The particles move fast in all directions.

Question 3

SC1a
1) Explain where energy is transferred to form and lose attractive forces.
2) Explain the states of matter at different melting and boiling points.

Answer 3

1) When attractive forces are formed, energy must be transferred from the particles to the surroundings.
When attractive forces are lost, energy must be transferred from the surroundings to the particles.
2) Below the melting point, the substance is solid.
Above the melting and below the boiling point, the substance is liquid. (You CAN’T say between the melting and boiling points)
Above the boiling point, the substance is gas.

Question 4

SC1a
1) What are the state changes as the temperature increases from a solid?
2) What are the state changes as the temperature decreases from a gas?
3) What is sublimation?

Answer 4

1) At the melting point, a substance melts, and at the boiling point the substance evaporates or boils.
2) At the boiling point, the substance condenses, and at the melting point, a substance freezes.
3) Sublimation is when a substance changes directly from solid to gas, or from gas to solid, without becoming a liquid in between.