The Particle Model

Question 1

What are the three states of matter?

Answer 1

solid, liquid, gas

Question 2

what is a particle?

Answer 2

smallest ‘part’ of a substance that can exist.

Everything is made of particles.

Different substances are made of different types of particles.

Question 3

solid arrangement, movement and forces?

Answer 3

One of the three ‘states of matter’.

· The particles are arranged in a fixed pattern – they cannot move out of position, but they can vibrate.

· A solid has a fixed shape and volume – the volume and shape cannot change.

forces of attraction are really strong.

Question 4

liquid arrangement, movement and forces?

Answer 4

One of the three ‘states of matter’.

· The particles are mostly touching but are randomly arranged (they are not in a pattern) – they cannot move away from each other, but they can move around over one another.

· A liquid has a fixed volume but the shape can change.

forces of attraction are mildly strong and weaker than solids.

Question 5

gas arrangement, movement and forces?

Answer 5

One of the three ‘states of matter’.

· The particles are very far apart and randomly arranged (they are not in a pattern) – they move around in straight lines, changing direction when they bump into another particle or wall.

· A gas has does not have a fixed shape or volume – the volume and shape can both change.

forces of attraction are weak. (weakest out of the states of matter)

Question 6

what is sublimation?

Answer 6

conversion of a substance from the solid to the gaseous state without its becoming liquid.

Question 7

melting…

Answer 7

occurs when a solid is heated and turns to a liquid

Question 8

boiling…

Answer 8

occurs when a liquid is evaporated/vaporised and turns into a gas

Question 9

condensing…

Answer 9

occurs when a gas is condensed and turns into a liquid

Question 10

freezing…

Answer 10

occurs when a liquid freezes/is frozen and turns into a solid

Question 11

what is a melting point?

Answer 11

temperature at which a substance melts (turns from solid to liquid) or freezes at (turns from liquid to solid).

For example, pure water has a melting point of 0°C, this means that if ice (solid water) warms up to 0°C it will start to melt. If water is cooled down it will start to freeze when it reaches 0°C.

Given temperature < melting point == Solid
Given temperature is between melting and boiling points == Liquid
Given temperature > boiling point == Gas

Question 12

what is a boiling point?

Answer 12

The temperature at which a substance boils (turns from liquid to gas) or condenses at (turns from gas to liquid).

For example, pure water has a boiling point of 100°C, this means that if water is heated to 100°C it will start to boil. If steam (water vapour or gas) is cooled down it will start to condense when it reaches 100°C.

Question 13

What happens in a physical change dissolving in terms of the particles and particle model?

Answer 13

In a physical change the nature of the substance, the particles of which it is composed and the numbers of particles remain unchanged

Dissolving happens when the attraction between the particles of the solvent and solute are strong enough to overcome the attraction of the particles of the solute for one another. Evaporation happens when water molecules move fast enough to break away from a solution and move into the air.

Given temperature < melting point == Solid
Given temperature is between melting and boiling points == Liquid
Given temperature > boiling point == Gas

Question 14

What state of matter would this substance be at:

The melting point of oxygen is -218°C and its boiling point is -183°C. Predict the state of oxygen at -200°C.

Answer 14

Liquid because it is in between the melting and boiling points.

Question 15

What state of matter would this substance be at:

Gold has a melting point of 1064.18°C (1337.33 K) and a
boiling point of 2700°C (2973.15 K)

Predict what state would gold be at 2742 degrees.

Answer 15

It will be a gas as gold is exposed to 2742 degrees which is higher than its boiling point

Question 16

vibrate…

Answer 16

Small movements from side to side.

Question 17

forces of attraction…

Answer 17

Forces of attraction are what holds particles together.

Question 18

property…

Answer 18

A property of a substance describes what it is like

e.g. does it have a fixed shape and volume? Can it be compressed? Does it have a high or low density?

Question 19

what is density and how do we work it out?

Answer 19

The mass of 1cm3 of a substance.

For example, water has a density of 1 gram per centimetre cubed (1 g/cm3), this means that 1cm3 of water would have a mass of 1g.

density = mass / volume

Substances with a high density ‘feel’ heavy for their size – liquids and solids tend to have high densities because their particles are packed close together.

Substances with a low density ‘feel’ light for their size – gases tend to have low densities because their particles are spaced out.

Question 20

volume…

Answer 20

amount of ‘space’ something takes up.

In science we measure it in centimetres cubed (cm3) which are the same as millilitres (ml).

Question 21

compress…

Answer 21

If you can compress a substance you can squash it into a smaller space.

Gases can be compressed because the particles are far apart but liquids and solids cannot be compressed because the particles are already touching so they cannot get any closer together.

Question 22

arrangement…

Answer 22

How something (in chemistry we are usually talking about particles) is arranged or positioned,

e.g. are the particles arranged in a pattern or at random?

Question 23

flow…

Answer 23

Moving from one place to another in a constant stream,

e.g. water flows when you pour it from a jug into a glass, gas flows out of the gas tap when you turn it on