1.1 States of matter

Question 1

What structure do particles in a solid form?

Answer 1

Regular lattice structure

Question 2

Materials come in three different forms. What are these forms?

Answer 2

• Solid
• Liquid
• Gas

Question 3

What is the model called which we use to explain how particles in a material behave?

Answer 3

Particle theory

Question 4

Describe the particle theory for solid materials

Answer 4

• Strong forces of attraction between particles, holds them close together in fixed positions to form a very regular lattice arrangement
• Particles don’t move from their positions, all solids keep a definite shape and volume
• The particles vibrate about their positions, the hotter the solid becomes, the more they vibrate

Question 5

Describe the particle theory of liquids

Answer 5

• The forces of attraction between particles are weaker than in solids. Randomly arranged and free to move past each other, but they tend to stick closely together
• Liquids have a definite volume but don’t keep a definite shape
• Particles are constantly moving with random motion. Hotter the liquid gets, the faster they move

Question 6

Describe the particle theory of gases

Answer 6

• Particles are well separated so there’s no attraction between them - they’re free to move and are far apart. Particles move in straight lines
• Gases don’t keep a definite shape or volume
• Particles move constantly with random motion. The hotter the gas gets, the faster they move. gases either expand when heated, or their pressure increases

Question 7

Substances can change from one state of matter to another. When that happens, the change is a ___________ _______

Answer 7

Physical change

Question 8

During a chemical reaction, what happens to the particles inside a material?

Answer 8

Bonds between atoms break and the atoms change places - the atoms from the substances you start off with (the reactants) rearrange themselves to form different chemicals.

Question 9

Compared to physical changes, chemical changes are often easy/hard to reverse

Answer 9

Hard

Question 10

What happens when a solid is heated?

Answer 10

• It’s particles gain more energy, this makes the particles vibrate more which weakens the forces that hold the solid together
• At the melting point, the particles have enough energy to break free from their positions. This is called MELTING and the solid turns into a liquid

Question 11

What is it called when a solid turns into a liquid?

Answer 11

Melting

Question 12

What happens when a liquid is heated?

Answer 12

• The particles get even more energy, this energy makes the particles move faster, which weakens and breaks the bonds holding the particles together
• At the boiling point, the particles have enough energy to break all of their bonds. This is BOILING. The liquid becomes a gas

Question 13

What is it called when a liquid turns into a gas?

Answer 13

Boiling

Question 14

What happens when a gas cools?

Answer 14

• The particles no longer have enough energy to overcome the forces of attraction between them, bonds form between the particles
• At the boiling point, so ,amu bonds have formed between the gas particles that the gas becomes a liquid. This is called CONDENSING

Question 15

What is it called when a gas turns into a liquid?

Answer 15

Condensing

Question 16

What happens when a liquid cools?

Answer 16

• The particles have less energy, so move around less. There’s not enough energy to overcome the attraction between the particles, so more bonds form between them
• At the melting point, so many bonds have formed between the particles that they’re held in place. The liquid becomes a solid. This is FREEZING

Question 17

What is it called when a liquid turns into a solid?

Answer 17

Freezing

Question 18

The particle model (sometimes kinetic model) has 3 main assumptions. These are that the particles are:

Answer 18

• Small
• Inelastic
• Spheres

Question 19

When a solid is heated, energy is transferred to the particles’ __________ energy stores, causing them to vibrate faster

Answer 19

Kinetic

Question 20

If a gas is heated when it is trapped within a container that cannot expand, it means that the ________ of the gas is fixed, and so the _________ inside the container increases

Answer 20

Volume, pressure

Question 21

Explain why hot water evaporates more quickly than cold water

Answer 21

Hot water molecules have more energy to break the intermolecular forces between water molecules