States of matter

Question 1

What’s the arrangement of gas particles?

Answer 1

random

Question 2

How do gas particles move?

Answer 2

fast in all directions

Question 3

What’s the arrangement of solid particles?

Answer 3

regular pattern

Question 4

What’s the arrangement of liquid particles?

Answer 4

close together

Question 5

What’s the movement of solid particles?

Answer 5

They vibrate about fixed positions

Question 6

How do liquid particles move?

Answer 6

around each other

Question 7

How much energy do solid particles have?

Answer 7

little/the least

Question 8

How much energy do gas particles have?

Answer 8

lots/the most

Question 9

What 3 things happen during a state change?

Answer 9

• Energy is transferred to or from the particles.
• The arrangement of particles changes.
• The movement of particles changes.

Question 10

What does a substance do at it’s melting point?

Answer 10

• Melt if energy is transferred to the particle

- Freeze if energy is transferred to the surroundings

Question 11

What does a substance do at its boiling point?

Answer 11

• Boil if energy is transferred to the particle

- Condense if energy is transferred to the surroundings

Question 12

When does a substance evaporate?

Answer 12

If it changes from a liquid to a gas below its boiling point.

• Particles with high enough energy leave the surface of the liquid
• The remaining particles have less energy
• The liquid cools down unless it is heated

Question 13

What theory models the states of matter, with particles described as hard spheres?

Answer 13

The particle theory.

Question 14

The table shows some data about bromine.

Melting point (degrees C): -7
Boiling point (degrees C): 59

a) Predict the state of bromine at 25 degrees C.
b) Describe, in terms of the particle theory, what happens when bromine boils.

Answer 14

a) liquid
b) Forces of attraction between bromine particles are overcome and the particles move far apart.
The particles no longer move around each other, but move quickly in all directions.

Question 15

Are state changes physical changes or chemical changes?

Answer 15

Physical changes, they can be undone and what they are made of doesn’t change.

Question 16

Naphthalene is a solid that can change directly from a solid to a gas at room temperature.
Name this change of state, and describe what happens to the particles.

Answer 16

sublimation
Forces of attraction between the particles are overcome as energy is transferred to the particles.
Arrangement changes from regular to random.
Arrangement changes from close together to far apart.
Particles no longer just vibrate about fixed positions, but can move quickly in all directions.

Question 17

state change from solid to liquid

Answer 17

melting

Question 18

state change from liquid to solid.

Answer 18

freezing

Question 19

state change from solid to gas.

Answer 19

sublimation

Question 20

state change from gas to solid.

Answer 20

deposition

Question 21

state change from liquid to gas.

Answer 21

evaporating or boiling

Question 22

state change from gas to liquid.

Answer 22

condensing

Question 23

Are the forces of attraction between particles strongest in solids or gases?

Answer 23

Solids

Question 24

What happens during melting?

Answer 24

The particles move out of a fixed position. They move around each other and have a random arrangement. The forces of attraction between them weaken, they vibrate faster and have more energy. The particles move faster.

Question 25

What happens during evaporating?

Answer 25

The forces of attraction weaken, the particles stay in a random arrangement. The particles move away from each other and move fast in all directions. The move very quickly and have lots of energy. The particles get faster/vibrate faster.

Question 26

Explain what happens during condensing.

Answer 26

The particles lose energy, the forces of attraction grow stronger. The particles get slower and closer together.

Question 27

Describe the following for solid, liquid and gas - arrangement of particles, movement of particles, the particles relative energy.

Answer 27

Solid: The particles are in a fixed and regular position. They vibrate slightly. They have little energy.

Liquid: The particles are arranged randomly but are still touching. They move quickly over each other. They have more energy than a solid.

Gas: The particles are far apart and random. They move quickly in all directions until they bounce off something. They have a lot of/the most energy.

Question 28

Water molecules have forces of attraction between themselves. This is what holds the particles in their solid state.

What must happen to the strength of these attractive forces when changes of state happen, such as melting and evaporating? Explain your answer.

Answer 28

They weaken as the particles gain more energy and are able to move away from each other.

Question 29

What causes attractive forces to weaken or strengthen during changes of state?

Answer 29

The particles gaining or losing energy.

Question 30

What does a horizontal line on a temperature/time graph represent?

Answer 30

A state change taking place.