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Science > Physics (P4) > Flashcards

Physics (P4) Flashcards

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1
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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2
Q

What is the size of the average atom?

A

1 × 10-10 or 0.1nm

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3
Q

What is a sub-atomic particle?

A

A particle that makes up the atom:
Protons
Neutrons
Electrons

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4
Q

What is the atomic nucleus?

A

The central part of the atom

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5
Q

What is the mass and charge of a proton?

A

Mass= 1
Charge= +1

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6
Q

What is the mass and charge of a neutron?

A

Mass= 1
Charge= 0

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7
Q

What is the mass and charge of an electron?

A

Mass= 0
Charge= -1

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8
Q

What is the overall charge of an atom?

A

Neutral

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9
Q

What is the charge of the nucleus?

A

Positive

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10
Q

What does the mass number tell you?

A

Total number of protons and neutrons

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11
Q

What does the atomic number tell you?

A

Number of protons

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12
Q

Which sub-atomic particles are in the nucleus?

A

Protons and Neutrons

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13
Q

Which sub-atomic particles orbit the nucleus?

A

Electrons

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14
Q

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

A

Protons
e.g if it has 2 protons it must be a helium atom

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15
Q

Explain why atoms are overall neutral?

A

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

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16
Q

What is an isotope?

A

Atoms of the same element with a different number of neutrons

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16
Q

What is an ion?

A

An atom that is charged because it has lost or gained eletrons

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17
Q

What are the number of protons, neutrons and electrons in
19
F
9

A

Protons=9
Neutrons=10
Electroms=9

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18
Q

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

A

Negative charges spaced in a positive dough

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19
Q

Who discovered the ‘‘Plum pudding’’ model?

A

J.J Thompson

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20
Q

Describe the ‘‘Plum pudding’’ model?

A

The atom is a ball/sphere of positive charge with negative electrons embedded in it.

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21
Q

What is the ‘‘Nuclear’’ model of the atom?

A

Positive central nucleus surrounded by negative electrons
Most of the atom is empty space

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22
Q

Who discovered the ‘‘Nuclear’’ model?

A

Rutherford

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23
Q

Give 3 characteristics of the ‘‘Plum pudding’’ model

A

-Mass is evenly distributed
-Negative electrons are distributed throughout the atom
-The to is mostly a positively charged ‘‘dough’’

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24
Q

Give 3 characteristics of the ‘‘Nuclear model’’

A

-Mass in concentrated at the centre
-Electrons orbit the nucleus at a distance
-The atom is mostly empty space

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25
Q

Describe Rutherford’s Nuclear model

A

Electrons orbit around the nucleus at a specific distance

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26
Q

Describe the Gold foil experiment by Rutherford,

A

· Alpha particles directed towards a piece of gold foil.
· Most particles pass straight through foil
· Some is deflected through small angles
· Very small number of alpha particles are deflected back at the alpha source

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27
Q

State 3 conclusions from the gold foil / alpha scattering experiment

A

1) mass of an atom is concentrated in a nucleus in the centre
2) nucleus is positive
3) Atom is mostly empty space

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28
Q

What did Neil Bohr discover?

A

Electrons orbit the nucleus in shells (at specific distances from the nucleus)

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29
Q

When is energy level high?

A

When the electron is further away from the nucleus

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30
Q

What happens if electrons are given energy?

A

They can move up energy levels

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31
Q

What needs to be absorbed for an electron to move to a higher energy level?

A

Photon
Electromagnetic wave

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32
Q

What happens in the ground state?

A

Electron is closest to the nucleus and has the lowest energy

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33
Q

What happens in the absorption state?

A

Electron absorbs energy from EM wave of photon

34
Q

What happens in the excitation state/

A

Electron goes up an energy level

35
Q

What is de-excitation?

A

Electron have too much energy and emits energy to go down to a lower energy level

36
Q

What is ionistaion?

A

Removal of electrons from atoms leaving them with an overall charge

37
Q

What change causes an atom to emit light?

A

De-excitation

38
Q

What makes an atom radioactive?

A

Has an unstable nucleus and therfore releases energy in the form of particles or EM waves

39
Q

How can an unstable nuclei become stable?

A

It can decay by giving out certain types of radiation

40
Q

What is radioactive activity?

A

The number of particles emitted per second

41
Q

What is count rate?

A

The measure number of particles detected per second

42
Q

What is the unit for radioactive activity?

A

Becquerels

43
Q

What type of process is radioactive decay?

A

Random process

44
Q

What is the equipment for measuring radiation?

A

Geiger-Muller tube or Geiger counter

45
Q

Name the 3 types of nuclear radiation

A

Alpha
Beta
Gamma

46
Q

Describe the structure of an alpha particle

A

2 neutrons & 2 protons (helium nucleus)

47
Q

What is a beta particle?

A

A high energy electron

48
Q

What is a gamma ray?

A

A high energy electromagnetic wave from the nucleus

49
Q

What is the mass and charge of an alpha particle?

A

Mass= 4
Charge= +2

50
Q

What is the mass and charge of beta?

A

Mass= 0
Charge= -1

51
Q

What is the mass and charge of gamma?

A

Gamma doesn’t have a mass or charge

52
Q

How does beta decay occur?

A

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

53
Q

How is the nuclear equation written?

A

Unstable → stable + radiation
nucleus nucleus

54
Q

How far can alpha travel?

A

Only travels a few cm though air

55
Q

How far can beta travel?

A

Up to 1m

56
Q

How far can Gamma travel?

A

Many kilometres

57
Q

Which radiation is mostly penetrating?

A

Gamma

58
Q

Which radiation is the least penetrating?

A

Alpha

59
Q

Describe the ionising power of Alpha, Beta and Gamma

A

Alpha – strongly ionising
Beta – weakly ionising
Gamma – very weakly ionising

60
Q

Which material can stop Alpha?

A

Paper

61
Q

Which material can stop Beta?

A

Aluminium

62
Q

Which material can stop Gamma?

A

Thick lead

63
Q

Define ‘Half-life’ ?

A

The time taken for half of the radioactive nuclei to decay

64
Q

If there are 1000 nuclei in a radioactive sample, how many should be left after 2 half-lives?

A

1000 → 500 → 250

65
Q

After one half-life which things will halve?

A

Number of unstable nuclei
Mass of radioactive isotope
Activity
Count rate

66
Q

What is Irradiation?

A

When an object is exposed to radiation (The object is now radioactive)

67
Q

What is Contamination?

A

When radioactive material gets onto or in an object (The object is now radioactive)

68
Q

What is direct radiation damage caused by?

A

Mostly caused by alpha and beta by hitting the skin and transferring energy

69
Q

What is indirect radiation damage caused by?

A

Mostly caused by gamma by ionising atoms in cells

70
Q

Define ‘background radiation’

A

Radiation around us all the time.

71
Q

State 4 natural sources of background radiation

A

Radon Gas
Rocks
Soil
cosmic rays

72
Q

Where does most background radiation come from?

A

Radon gas

73
Q

What is radon gas?

A

Radioactive gas produced by rocks that have small amounts of uranium

74
Q

State 3 man made sources of background radiation

A

· Fallout from nuclear weapons
testing
· Nuclear accidents
· Nuclear Power stations

75
Q

State 2 medical uses of radiation

A

Radioactive traces
Radiotherpy

76
Q

State the risk of using radiation

A

Tissue damage

77
Q

Would a long or short half-life radioactive material be more dangerous in the long term?

A

Long half-life material.

78
Q

What kind of radiation is used to look at internal organs?

A

Beta

79
Q

What is radioactive traces used for?

A

Diagnosis

80
Q

Which nuclear radiation is used for radioactive traces?

A

Beta and Gamma

81
Q

What kind of radiation is used to look at internal organs?

A

External

82
Q
A

Science (12 decks)

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