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Science 3x > P4 (physics)(book & booklet) > Flashcards

P4 (physics)(book & booklet) Flashcards

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1
Q

What does the mass number tell you?

A

The number of particles in the nucleus (numbers of proton and neutrons)

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2
Q

What does the atomic number tell you?

A

Number of protons

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3
Q

How do you find out the number of neutrons?

A

Mass number - atomic number

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4
Q

What is the number of electrons equal to ?

A

Number of electrons = number or protons

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5
Q

What is the charge of a neutron?

A

0

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6
Q

What is the charge of a proton?

A

+1

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7
Q

What is the charge of a electron?

A

-1

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8
Q

What charge is the nucleus?

A

Positive (2+)

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9
Q

What is the overall charge of an atom?

A

Neutral

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10
Q

Define isotope

A

Atoms of the same element but with a different number of neutrons

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11
Q

Describe the plum pudding model

A

No nucleus
Mass is spread out
Electrons embedded in a positive charge

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12
Q

Describe Rutherford’s nuclear model

A

Mass is concentrated in the centre
Electrons orbit the positive nucleus
Most of the atom is empty spaced

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13
Q

What is an atom ?

A

The smallest piece of an element that still has the properties of that element. A building-block of matter

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14
Q

What is the size of an average atom?

A

1x 10^-10 or 0.1nm

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15
Q

What is a sub-atomic particle?

A

A particle that makes up the atom

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16
Q

Name the 3 sub-atomic particle

A

Proton
Neutron
Electron

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17
Q

What is the atomic nucleus ?

A

The central part of the atom (containing protons and neutrons)

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18
Q

What is the mass of a proton?

A

1

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19
Q

What is the mass of a neutron?

A

1

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20
Q

What is the mass of an electron?

A

0

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21
Q

Which sub-atomic particles are in the nucleus?

A

Protons and neutrons

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22
Q

Which sub-atomic particles orbit the nucleus?

A

Electrons

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23
Q

Which sub-atomic particle defines which element the atom is?

A

Proton

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24
Q

Explain why atoms are overall neutral (3)

A

Protons are positive
Electrons are negative
Atoms have the same number of protons and electrons so they cancel out

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25
Q

What is an ion?

A

An atom that is charged becuase it has lost or gained electrons

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26
Q

What was the ‘plum pudding’ model of the atom?

A

Negative charges spaced in a positive dough

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27
Q

What is the ‘nuclear’ model of the atom?

A

Positive central nucleus surrounded by negative electrons- most of atoms is empty spaced

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28
Q

What is gamma radiation?

A

An electromagnetic wave from the nucleus

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29
Q

Describe the structure of an alpha particle

A

A helium nucleus - 2 protons and 2 neutrons

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30
Q

What is a beta particle?

A

A fast moving electron

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31
Q

What are the three types of ‘nuclear’ radiation?

A

Alpha , beta particle , gamma ray

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32
Q

What is the unit of “activity” for a radioactive isotope?

A

Becquerels (Bq)

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33
Q

What is contamination?

A

When radioactive material gets into an object
The object is now radioactive

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34
Q

What is irradiation?

A

When an object is exposed to radiation
The object doesnt become radioactive

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35
Q

Which is the most penetrating radioactive emission?

A

Gamma

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36
Q

Which is the least penetrating radioactive emission?

A

Alpha

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37
Q

Which materials are able to stop each type of radiation?

A

Alpha = paper
Beta = aluminium
Gamma = thick lead or thick concrete

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38
Q

Describe the ionising power of alpha , beta and gamma

A

Alpha = strongly ionising (dangerous can destroy and damage cells and tissues very quickly)
Beta = weakly ionising
Gamma = very weakly ionising

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39
Q

How does beta decay occur?

A

A neutron in the nucleus decays to make a proton and an electron. The electron exits the nucleus as a beta particle and the proton stays in the nucleus

40
Q

what does the term ‘half-life’ mean?

A

Time taken for the number of unstable nuclei to half

41
Q

Who set up an experiment, where alpha particles were fired?

A

Rutherford

42
Q

What did Rutherford fire the alpha particles at?

A

An incredibly thin piece of gold

43
Q

What did Rutherford fire in his golf foil experiment?

A

Alpha particles

44
Q

What was Rutherford expecting?

A

All of the particles to pass through unaffected

45
Q

What happened to some of the particles he fired and why was that?

A

Many of the particles were deflected , with some almost bouncing back to where they came from This showed that the nucleus at the centre must be positive because positives repels from each other

46
Q

What is it called when electrons could only be found at specific distances from the nucleus?

A

Energy levels or shells

47
Q

The further away from the nucleus , the higher the what?

A

The higher the Energy levels or shells

48
Q

What can the electrons do if they are given energy (by absorbing electromagnetic radiation)?

A

They can move up energy levels

49
Q

Can this process (excitation) be reversed?

A

Yes this process can happen in reverse

50
Q

If an electron moving closer to the nucleus (down an energy level) what will it give out?

A

It will give out some electromagnetic radiation or photon

51
Q

What is meant by when some atoms are ‘radioactive’?

A

They have an unstable nucleus, that wants to decay. It can decay to become more stable by giving out certain types of radiation

52
Q

What is meant by activity?

A

The number of decays/particles emitted per/each second. The unit of activity is the becquerel (Bq). 1 Bq is equal to one decay per second

53
Q

What kind of process is radioactive decay?

A

A random process

54
Q

What does it mean if radioactive decay is a Radom process?

A

This means you cant predict which atom will decay next, or how long it will take for any individual atom to decay

55
Q

When an unstable nucleus decay , which three types of radiation can it emit?

A

Alpha
Beta
Gamma

56
Q

What is the change to the mother nucleus on an alpha particle?

A

Nucleus loses 2 protons and 2 neutrons

57
Q

What is the change to the mother nucleus on a beta particle?

A

The nucleus loses a neutron and gains proton

58
Q

What is the change to the mother nucleus on gamma?

A

The nucleus has less energy

59
Q

State the decay equation for alpha?

A

4
α
2

60
Q

How do you do the alpha decay equation?

A

Take 4 away from the mass number
Take 2 away from the atomic number

61
Q

Write the beta decay equation

A

0
β
-1

62
Q

How do you solve the beta decay equation?

A

Mass number doesn’t change
Add 1 to the atomic number

63
Q

What is alpha’s range in air?

A

A few centimetres

64
Q

What is beta’s range in air ?

A

Up to 1m

65
Q

What is gamma’s range in air?

A

Many kilometres

66
Q

What is ground state?

A

Lowest energy and closest to the nucleus
(First shell)

67
Q

What is absorption stage?

A

Electrons absorbs energy from Em wave or a photon

68
Q

What is the excitation state?

A

Electron goes ‘’up’ an energy shell

69
Q

Define an excited atom

A

Electrons have too much energy

70
Q

What does the electron do to go down to a lower energy shell?

A

Emits energy

71
Q

What is ionisation?

A

Removal of electrons from atoms ,leaving them with an overall charge

72
Q

What does ionisation create?

A

Ions

73
Q

What is the mass and charge of an alpha particles?

A

Mass = 4 because it has 4 atoms
Charge = 2+

74
Q

What is the mass and charge of a beta particle?

A

Charge = -1
Mass = 0

75
Q

What does em stand for?

A

Electromagnetic

76
Q

What will the unstable nucleus do ?

A

Unstable nucleus → stabler nucleus + radiation

77
Q

Are alpha particles big or small?

A

Big

78
Q

What are direct radiation damage mostly caused by?

A

Alpha and beta ‘hitting’ the skin and transferring energy

79
Q

What are indirect radiation damage mostly caused by?

A

Gamma by ionising atoms in cells

80
Q

What forces act on the particles in the nucleus of an atom?

A

Intermolecular

81
Q

What is the difference between the activity and the count rate of a radioactive source?

A

Activity → overall
Count rate → detected

82
Q

What was JJ Thompson’s discovery that lead to the plum pudding model of the atom?

A

Electrons

83
Q

Why is alpha particles most ionising?

A

Biggest particle out of Gamma and Beta

84
Q

Why is gamma the most penetrating?

A

Because it is a EM wave

85
Q

Name the three uses of radiation

A

Sterilisation
Smoke detectors
Paper/metal sheet manufacturing

86
Q

Explain which type of radiation is used for sterilisation

A

Gamma
Irradiation
Most penetrating so it can kill any bacteria
Least ionising

87
Q

Explain which type of radiation is used for a smoke detector

A

Alpha particle
Ionising enough to ionise air particles, completing the circuit
Easily absorbed (smoke)
Can’t travel far (~2cm) so it is safe to use

87
Q

Explain which type of radiation is used for paper/metal sheet manufacturing

A

Beta radiation
Weakly ionising
Fairly penetrating

88
Q

Define radon gas

A

Radioactive gas produced by rocks because most have small amounts of Uranian
→ Made up 49% of the background radiation

89
Q

What is the Equation for real activity?

A

Real activity = measured activity - background activity

90
Q

Give examples of the damage a radiation can cause

A

Burns
Tumours (cancer)

91
Q

Define radioactive tracer

A

A radioactive source combined with a drug or biochemical agent. Injected into patient to help with diagnosis of disease
→ Radioactive sources of beta or gamma

92
Q

Why is alpha not used for radioactive tracer?

A

Too ionising and is not penetrating so it can not travel far

93
Q

What are the two types of radiotherapy?

A

Internal radiotherapy
External radiotherapy

94
Q

Define internal radiotherapy

A

Direct damage to tumours cells
→ Alpha or beta particles

95
Q

Define external radiotherapy

A

Targeting tumours from outside with gamma rays

Science 3x (12 decks)

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