Topic 6 - Radioactivity Flashcards

1
Q

1 What is the difference between an atom and a molecule?

A

A molecule is two or more atoms bonded together.

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2
Q

2 What is an element?

A

substance where all atoms have the same atomic number/number of protons

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3
Q

3 What is the part in the middle of an atom called?

A

nucleus

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4
Q

4 Name two subatomic particles.

A

any two from: proton, electron, neutron

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5
Q

5 What are the negatively charged particles in an atom called?

A

electrons

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6
Q

6 What are the positively charged particles in an atom called?

A

protons

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7
Q

7 Where is most of the mass of an atom concentrated?

A

nucleus

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8
Q

8 Which subatomic particles have a negligible mass?

A

electrons

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9
Q

9 How did scientists discover that atoms had tiny nuclei?

A

fired particles at atoms/gold sheet

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10
Q

10 Who investigated atoms in this way?

A

Rutherford

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11
Q

11 Which of the following is approximately the diameter of an atom ? a hundredth of a millimetre, a thousandth of a millimetre or a millionth of a millimetre?

A

millionth of a millimetre

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12
Q

12 What charge do electrons have?

A

negative, or -1

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13
Q

13 How much mass do electrons have?

A

negligible / hardly any

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14
Q

14 In Thompson?s model, the atom was positively charged with tiny negative charges in it. What was this model called?

A

plum pudding model

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15
Q

15 Rutherford investigated the structure of the atom. What did he do?

A

He fired alpha particles at gold foil.

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16
Q

16 What happened to most of the alpha particles in Rutherford?s experiment?

A

went straight through

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17
Q

17 Why did Rutherford conclude that most of the mass of the atom was in the centre?

A

A few particles bounced back.

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18
Q

18 What is the relative mass of a proton?

A

1

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19
Q

19 What are isotopes?

A

atoms of the same element with different masses

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20
Q

20 Which subatomic particle has no charge?

A

neutron

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21
Q

21 What is another name for nucleon number?

A

mass number

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22
Q

22 What is the mass number of an atom?

A

total number of protons and neutrons

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23
Q

23 What is the atomic number of an atom?

A

number of protons

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24
Q

24 What is another name for atomic number?

A

proton number

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25
Q

25 What is the relative mass of a neutron?

A

1

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26
Q

26 What is the relative charge on a proton?

A

1

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27
Q

27 What is different between two isotopes of the same element?

A

number of neutrons in the atomic nucleus

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28
Q

28 How are electrons arranged in an atom?

A

shells/orbits/energy levels

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29
Q

29 What is ionisation?

A

when an atom gains or loses an electron

30
Q

30 Where are the positive charges in an atom?

A

nucleus

31
Q

31 What happens to one or more electrons when an atom gains energy?

A

jump to higher orbits/shells/energy levels

32
Q

32 Name two ways in which an atom can gain energy.

A

any two from: by heating, by electricity, by electromagnetic radiation

33
Q

33 What happens to electrons when the atom loses energy?

A

They fall to a lower orbit/shell/energy level.

34
Q

34 What is ionisation?

A

when an atom absorbs enough energy to let an electron escape completely

35
Q

35 What charge does an ion have when it has lost an electron?

A

positive

36
Q

36 Name one source of background radiation in everyday life.

A

any sensible source, such as space, food, rocks etc.

37
Q

37 Name one thing that can detect radiation.

A

Geiger Muller tube/photographic film

38
Q

38 What is ionising radiation?

A

radiation that can cause atoms to form ions

39
Q

39 Is most background radiation natural or from human causes?

A

natural

40
Q

40 Where does radon gas come from?

A

uranium in some rocks

41
Q

41 What are cosmic rays?

A

charged particles from stars

42
Q

42 Why is background radiation different in different places?

A

different rocks and/or building materials

43
Q

43 What happens to photographic film when radiation hits it?

A

darkens

44
Q

45 What is a count rate?

A

the number of clicks/the number of radiation events detected per second

45
Q

46 Which high-frequency electromagnetic waves can be produced by radioactive decay?

A

gamma rays

46
Q

47 What is an alpha particle?

A

helium nucleus, or two protons and two neutrons

47
Q

48 What is a beta particle?

A

electron ejected from the nucleus of an atom/high-speed electron

48
Q

49 What is the relative mass of an alpha particle?

A

4

49
Q

50 What is the relative charge on an alpha particle?

A

2

50
Q

51 What is the relative charge on a beta particle?

A

1

51
Q

52 What is the relative charge on a positron?

A

1

52
Q

53 Which form of radiation is the most penetrating?

A

gamma rays

53
Q

54 Which form of radiation is the most ionising?

A

alpha particles

54
Q

55 What happens to the nucleus of an atom when it emits an alpha particle?

A

becomes more stable/changes to a different element

55
Q

56 What happens to the nucleus of an atom if it ejects a neutron?

A

changes to a different isotope of the same element

56
Q

57 What happens to the atomic number of a nucleus when an alpha particle is emitted?

A

It goes down by 2.

57
Q

58 What happens to the mass number of a nucleus when an alpha particle is emitted?

A

It goes down by 4.

58
Q

59 How is a beta particle formed?

A

a neutron changes into a proton and an electron

59
Q

60 What happens to the atomic number of a nucleus when a beta particle is emitted?

A

It goes up by 1.

60
Q

61 How is a positron formed?

A

A proton changes into a neutron and a positron.

61
Q

62 What happens to the atomic number of a nucleus when a positron is emitted?

A

It goes down by 1.

62
Q

63 What does the activity of a radioactive source refer to?

A

the number of decays per second

63
Q

64 What does half-life mean?

A

the time it takes for the activity to halve, or for the number of unstable nuclei to halve

64
Q

65 What is the unit for measuring the activity of a source?

A

becquerel

65
Q

66 What does 1 becquerel represent?

A

1 decay per second

66
Q

67 Why can we not predict exactly how many nuclei will decay each second?

A

Decay is a random process.

67
Q

68 How does the activity of a radioactive source change over time?

A

It gets less.

68
Q

69 What does the half-life tell you about the activity of a sample of radioactive material?

A

the time until the activity falls by half

69
Q

70 Name one disease that can be caused by radiation.

A

cancer

70
Q

71 Name one type of job that may involve being exposed to nuclear radiation.

A

hospital worker/nurse/doctor or scientist or nuclear power station worker

71
Q

72 What has happened if you are contaminated by radioactive material?

A

you have got it on your skin or inside your body