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Physics Paper 1 > Unit 7 Radioactivity > Flashcards

Unit 7 Radioactivity Flashcards

1
Q

What is the radius of an Atom

A

1 times 10 to the minus 10 metres

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2
Q

What’s the size of a nucleus of an atom

A

1 times 10 to the minus 14 metres

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3
Q

What’s the charge of the nucleus and why

A

Positive because of the positive protons
Neutrons have no charge

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4
Q

Where in the atom is the electrons located

A

In the energy levels (shells)

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5
Q

The further the energy level ( away from nucleus) the …

A

Higher the energy level

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6
Q

How can electrons change energy levels

A

By absorbing or emoting energy

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7
Q

If an electron absorbs light what happens

A

It moves to a higher energy level

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8
Q

Describe what happens to the electron
-The suns rays passes through an electron

A

-The electron absorbs energy so it moves to a higher energy level
-Then it emits the energy so it moves back down

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9
Q

What does the atomic number tell us

A

The number of protons

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10
Q

What charge does an atom have

A

Zero neutral

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11
Q

What does the mass number tell us

A

The number of protons and neutrons

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12
Q

What’s an isotope

A

An atom of the same element but with a different number of neutrons

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13
Q

Who were the first people to think of atoms

A

Ancient Greeks

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14
Q

What did the Ancient Greeks believe about atoms

A
  • They believed everything was made of atoms
    -They were tiny spheres that cannot be divided
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15
Q

Who discovered the electrons

A

JJ Thompson

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16
Q

What was the model created after the discovery of electrons called

A

Plum pudding model

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17
Q

What did the plum pudding model suggest

A

An atom is a cloud of positive charge with negative electrons within it like plum in a plum pudding

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18
Q

Who discovered the nucleus and what was the method he used called

A

Earnest Rutherford
Alpha scattering

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19
Q

Describe the alpha scattering method

A
  • They used a thin piece of gold foil
  • Shoot dense alpha particles through it ( with a positive charge)
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20
Q

How did Rutherford come to conclusion there was a nucleus (three reasons)

A

Because when the alpha particles were shot through the foil they :
- Went straight through therefore most of the atom is empty space
-Deflected back therefore the centre of the was + because the alpha particles were repelled
- Bounced off the atom therefore most of the mass is in the centre

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21
Q

What was the name of the model created after the discovery of nucleus

A

Nuclear model

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22
Q

What did the nucleus model look like

A

The proton was at the centre with a ring of negatively charged electrons around it
Between them were empty space

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23
Q

Who discovered energy shells

A

Neil’s Bohr

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24
Q

Who discovered the neutrons and how

A

James Chadwick
Because there was a missing mass but with no charge

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25
26
What’s the symbol for an alpha particle
A fish swimming sideways
27
What’s the symbol for a beta particle
An electron
28
What’s the symbol for a gamma ray
A fish swimming downwards
29
State the atomic and mass number of an alpha particles
Mass number is 4 Atomic number is 2
30
What happens to the atomic and mass number of an atom emitting alpha particles
The atom loses 4 mass and 2 protons
31
Why do atoms emit alpha beta or gamma and what is this called
Because they have an unstable nucleus and it’s called radioactive decay
32
What’s the mass of a a) proton b) neutron c) electron
A) 1 B) 1 C) 1/2000
33
What’s the charge of an A) proton B) electron C) neutron
A) +1 B) -1 C) 0
34
What’s an isotope
An atom of the same element with a different number of neutron
35
Why are isotopes like to be radioactive
Because they have a unstable amount of neutrons in their nucleus
37
What is it called when the nucleus emit radiation
Radioactive decay
38
Radioactive decay is a _________ process
Random
39
What is activity
It’s the rate at which the unstable nucleus decays
40
How do isotopes become stable
By emitting radiation from the nucleus
40
What’s activity measured in
Becquerel (Bq) 1 decay per second
41
What device do we use to measure radioactivity
Geiger muller tube
42
What’s the count rate
The number of decays recorded each second by a detector
43
What does an alpha particle consist of and what atom is it the same as
2 protons and 2 neutrons It’s the same as a helium atom
44
What does a beta particle consist of
A negative electron
45
How is a beta particle formed within a radioactive substance
It’s formed when a neutron turns in to a proton and an electron
46
What’s a gamma ray
It’s a type of electromagnetic radiation
47
State the properties of an alpha particle
- Their range in air is 5cm - Their penetrating power is paper -Their strongly ionising
48
State the properties of a beta particle
- Their range in air is 15cm - Their penetrating power is 2-3mm of aluminium - Quite ionising
49
State the properties of gamma rays
- Their range in air is several metres - Their penetrating power is thick lead - Weakly ionising
50
What’s ionising power
When radiation collided with atoms so they lose electrons and form ions
51
Define half life
The time taken for a the number in the nucleus of a radioactive isotope to half
52
Define half life in terms of count rate
The time taken for the count rate from a radioactive substance to half
53
Define Irradiation
Exposing something to nuclear radiation
54
Does the object after being irritated become radioactive
No
55
How do staff working with alpha beta or gamma protect themselves
-By wearing lead aprons and gloves -Lead screens
56
Define radioactive contamination
When UNWANTED radioactive isotopes end up on materials
57
Define peer review
When scientists publish finding and are shared to other scientists
58
Define background radiation
The radiation already present without a radioactive isotope
59
State the natural causes of background radiation
- Radioactive rock (granite) - Cosmic rays (in space)
60
State the human causes of background radiation
- Nuclear weapon testing - Nuclear accidents
61
What factors affect exposure to background radiation
Location and Occupation
62
What’s radiation doses measured in
Sieverts
63
How are radioactive isotopes used in medicine
Exploring internal organs Destroying or controlling cancers
64
Give an example of an element that is large and unstable
Uranium
65
What happens to the nucleus during nuclear **fission**
The nucleus of the element splits
66
Name the first step of nuclear fission
A neutron is fired at the right speed toward the unstable nucleus Therefore it splits into two smaller nuclei
67
What are the products released during the first split in nuclear fission
- Two or three neutrons - Gamma radiation - Energy
68
What’s a chain reaction during nuclear fission
When the neutrons emitted from the first fission reaction go through the next nucleus and so on
69
What is nuclear **fusion**
When two light nuclei join together to form a heavier one
70
How is energy created during nuclear **fusion**
Some of the mass is converted to energy and is emitted as radiation

Physics Paper 1 (1 decks)

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