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Physics (P4) Flashcards

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
Give 3 characteristics of the ''Nuclear model''
-Mass in concentrated at the centre -Electrons orbit the nucleus at a distance -The atom is mostly empty space
25
Describe Rutherford's Nuclear model
Electrons orbit around the nucleus at a specific distance
26
Describe the Gold foil experiment by Rutherford,
· 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
27
State 3 conclusions from the gold foil / alpha scattering experiment
1) mass of an atom is concentrated in a nucleus in the centre 2) nucleus is positive 3) Atom is mostly empty space
28
What did Neil Bohr discover?
Electrons orbit the nucleus in shells (at specific distances from the nucleus)
29
When is energy level high?
When the electron is further away from the nucleus
30
What happens if electrons are given energy?
They can move up energy levels
31
What needs to be absorbed for an electron to move to a higher energy level?
Photon Electromagnetic wave
32
What happens in the ground state?
Electron is closest to the nucleus and has the lowest energy
33
What happens in the absorption state?
Electron absorbs energy from EM wave of photon
34
What happens in the excitation state/
Electron goes up an energy level
35
What is de-excitation?
Electron have too much energy and emits energy to go down to a lower energy level
36
What is ionistaion?
Removal of electrons from atoms leaving them with an overall charge
37
What change causes an atom to emit light?
De-excitation
38
What makes an atom radioactive?
Has an unstable nucleus and therfore releases energy in the form of particles or EM waves
39
How can an unstable nuclei become stable?
It can decay by giving out certain types of radiation
40
What is radioactive activity?
The number of particles emitted per second
41
What is count rate?
The measure number of particles detected per second
42
What is the unit for radioactive activity?
Becquerels
43
What type of process is radioactive decay?
Random process
44
What is the equipment for measuring radiation?
Geiger-Muller tube or Geiger counter
45
Name the 3 types of nuclear radiation
Alpha Beta Gamma
46
Describe the structure of an alpha particle
2 neutrons & 2 protons (helium nucleus)
47
What is a beta particle?
A high energy electron
48
What is a gamma ray?
A high energy electromagnetic wave from the nucleus
49
What is the mass and charge of an alpha particle?
Mass= 4 Charge= +2
50
What is the mass and charge of beta?
Mass= 0 Charge= -1
51
What is the mass and charge of gamma?
Gamma doesn't have a mass or charge
52
How does beta decay occur?
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
How is the nuclear equation written?
Unstable → stable + radiation nucleus nucleus
54
How far can alpha travel?
Only travels a few cm though air
55
How far can beta travel?
Up to 1m
56
How far can Gamma travel?
Many kilometres
57
Which radiation is mostly penetrating?
Gamma
58
Which radiation is the least penetrating?
Alpha
59
Describe the ionising power of Alpha, Beta and Gamma
Alpha – strongly ionising Beta – weakly ionising Gamma – very weakly ionising
60
Which material can stop Alpha?
Paper
61
Which material can stop Beta?
Aluminium
62
Which material can stop Gamma?
Thick lead
63
Define 'Half-life' ?
The time taken for half of the radioactive nuclei to decay
64
If there are 1000 nuclei in a radioactive sample, how many should be left after 2 half-lives?
1000 → 500 → 250
65
After one half-life which things will halve?
Number of unstable nuclei Mass of radioactive isotope Activity Count rate
66
What is Irradiation?
When an object is exposed to radiation (The object is now radioactive)
67
What is Contamination?
When radioactive material gets onto or in an object (The object is now radioactive)
68
What is direct radiation damage caused by?
Mostly caused by alpha and beta by hitting the skin and transferring energy
69
What is indirect radiation damage caused by?
Mostly caused by gamma by ionising atoms in cells
70
Define 'background radiation'
Radiation around us all the time.
71
State 4 natural sources of background radiation
Radon Gas Rocks Soil cosmic rays
72
Where does most background radiation come from?
Radon gas
73
What is radon gas?
Radioactive gas produced by rocks that have small amounts of uranium
74
State 3 man made sources of background radiation
· Fallout from nuclear weapons testing · Nuclear accidents · Nuclear Power stations
75
State 2 medical uses of radiation
Radioactive traces Radiotherpy
76
State the risk of using radiation
Tissue damage
77
Would a long or short half-life radioactive material be more dangerous in the long term?
Long half-life material.
78
What kind of radiation is used to look at internal organs?
Beta
79
What is radioactive traces used for?
Diagnosis
80
Which nuclear radiation is used for radioactive traces?
Beta and Gamma
81
What kind of radiation is used to look at internal organs?
External
82

Science (17 decks)

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