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8Ne Year 7 Science > 7C Matter > Flashcards

7C Matter Flashcards

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1
Q

How are particles arranged in a solid?

A

Closely packed, in rows and columns

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2
Q

How do particles move in a solid?

A

They vibrate in fixed positions

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3
Q

How do particles move in a liquid?

A

They flow over each other

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4
Q

How are particles arranged in a liquid?

A

Loosely packed, randomly, not in rows or columns

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5
Q

How are particles arranged in a gas?

A

Spread very far apart

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6
Q

Why can gases be compressed?

A

There is lots of space between the particles

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7
Q

Why do we use a model to represent the three states of matter?

A

We cannot see particles so it makes it easier to understand

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8
Q

Describe one limitation of the particle model

A

In reality: particles are not always spherical; the forces between particles or the energy of the particles is not shown

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9
Q

What is a change of state?

A

When a material changes from one state to another, e.g. melting from a solid to a liquid

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10
Q

Why are changes of state described as physical changes?

A

They are reversible, nothing new is formed and there is no temperature change

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11
Q

What happens to the particles in a solid when it melts?

A

They gain energy and move around more

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12
Q

What is the difference between evaporating and boiling?

A

Evaporation occurs at the surface of a liquid. Boiling occurs throughout the liquid

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13
Q

What is the change of state where a liquid is cooled to form a solid?

A

Freezing

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14
Q

What happens to the forces between particles when a gas condenses?

A

Forces become stronger

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15
Q

What two conditions are needed for sublimation to occur?

A

High temperature and pressure

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16
Q

Why doesn’t the temperature of a material change during a change of state?

A

The energy is used to overcome the forces holding the particles together

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17
Q

Why can particles in gases and liquids move around?

A

More energy than in solids and weaker forces holding them in place

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18
Q

What is Brownian motion?

A

Random movement of particles

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19
Q

Define what a fluid is

A

A substance in which particles are able to move

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20
Q

What is pressure?

A

A force caused by the particles colliding with the walls of a container

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21
Q

Why does an increase in temperature cause an increase in pressure?

A

More energy, move around more, collide with walls of the container more often

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22
Q

Why does a decrease in the number of particles cause a decrease in pressure?

A

Fewer particles means fewer collisions with the walls of the container

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23
Q

Why does an increase in container volume cause a decrease in pressure?

A

More space for the particles to move around means that they are more likely to collide with the walls of the container

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24
Q

Why is it dangerous if the pressure of a contained gas increases too much?

A

It may explode

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25
Q

Define diffusion

A

The movement of particles from high concentration to low concentration

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26
Q

Why does diffusion not occur in solids?

A

The particles don’t move

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27
Q

What is a concentration gradient?

A

A difference in concentration between two areas

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28
Q

Define equilibrium

A

When particles are evenly spread

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29
Q

Why does increasing temperature make diffusion faster?

A

The particles have more energy,move faster and therefore spread out more quickly.

30
Q

How does a low concentration gradient affect diffusion?

A

The lower the gradient the slower the particles will spread out

31
Q

How does increasing the diffusion distance affect diffusion?

A

Increasing the distance means the particles need to travel further it therefore takes longer

32
Q

Give an example of diffusion

A

Perfume/ air freshener spreading out

33
Q

What is a pure substance?

A

A substance made up of only one type of element or compound

34
Q

Give an example of a pure substance

A

Pure water, gold

35
Q

How is the everyday definition of pure different to the scientific meaning?

A

In everyday language, pure means that nothing has been added to it to change it

36
Q

What is a mixture?

A

Contains two or more different substances which are not chemically joined

37
Q

Give an example of a mixture

A

Orange juice, sea water, air

38
Q

Why can mixtures be easily separated?

A

Yes as they are not chemically joined

39
Q

How can mixtures of solids and liquids be separated?

A

Filtration, evaporation and distillation

40
Q

Which technique is used to separate the different coloured dyes in pen ink?

A

Chromatography

41
Q

What is a separating technique?

A

A physical process which separates mixtures

42
Q

When filtering a mixture, what is collected in the filter paper?

A

Insoluble solids

43
Q

Why might distillation be used instead of evaporation when separating a mixture of salt and water?

A

Distillation is used if we want to separate the liquid from the mixture

44
Q

What two changes of state occur during distillation?

A

Evaporation, condensation

45
Q

What is a sieve?

A

A tray with very small holes to allow small solids to pass through but stop large solids passing through

46
Q

How do you separate a mixture of multiple solids?

A

Use sieves with different sized holes

47
Q

Why are the different dyes separated during chromatography?

A

Different sized dye particles are carried different distances up the paper

48
Q

Why can’t a magnet be used to separate a mixture of copper and sand?

A

Neither copper nor sand is magnetic

49
Q

What is a soluble substance?

A

A substance which dissolves

50
Q

What is an insoluble substance?

A

A substance which does not dissolve

51
Q

Define solution

A

A mixture of solute and solvent

52
Q

What does a solution look like?

A

Clear, can be different colours

53
Q

Give two examples of solvents

A

Water and ethanol

54
Q

What is a suspension?

A

Insoluble solid suspended in a liquid

55
Q

What do we mean when we say that a substance has a high solubility?

A

Lots of solute will dissolve in a certain volume of solvent

56
Q

How can you speed up the rate that sugar dissolves in tea?

A

Heat it, stir it, break it down into smaller pieces (increase surface area)

57
Q

What is chromatography used to do?

A

Separate a mixture of soluble substances

58
Q

What is the stationary phase?

A

The paper (which does not move)

59
Q

What is the mobile phase?

A

The solvent (which does move)

60
Q

State why the substances move different distances up the paper

A

The differentdissolvedsubstances in a mixture are attracted to the two phases in different proportions.

61
Q

What will a pure substance look like on a chromatogram?

A

One spot

62
Q

How does a chromatogram tell you how many substances are in a mixture?

A

Count how many spots there are

63
Q

What will happen if the origin line is drawn in pen?

A

It will travel up the chromatography paper and interfere with the inks.

64
Q

Why does the solvent level need to be below the origin line?

A

So the inks do not dissolve in the water

65
Q

Name the three substances you are going to separate.

A

Sand, salt and iron filings

66
Q

Why do you need to wear goggles and an apron?

A

To prevent anything getting on clothes or in eyes

67
Q

In what order is each substance separated?

A

Iron filings, sand, salt

68
Q

How do you prepare the filter paper for filtration?

A

Fold in half, fold in half again, separate one of the sides from the other three and open out into a cone

69
Q

How will you evaporate the water from the evaporating basin?

A

Heat over a water bath

70
Q

How do you know when to turn off the Bunsen burner?

A

When almost all of the water has evaporated

8Ne Year 7 Science (11 decks)

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