The Atom and Radiation

Question 1

What did John Dalton discover?

Answer 1

Atoms

Question 2

What did J.J Thompson discover?

Answer 2

Electrons and the Plum Pudding Model

Question 3

What did Rutherford discover?

Answer 3

Nucleus and the Nuclear model

Question 4

What did Niels Bohr discover?

Answer 4

Protons

Question 5

What did James Chadwick discover?

Answer 5

Neutrons

Question 6

How big is an atom?

Answer 6

1 x 10/-10

Question 7

How do electrons move?

Answer 7

If they gain energy by absorbing EM radiation they move to a higher energy level, further from the nucleus
If they release EM radiation they move to a lower energy level, closer to the nucleus

Question 8

What do unstable isotopes do?

Answer 8

Decay into other elements by giving out radiation (Known as radioactive decay)

Question 9

Name the three types of radiation

Answer 9

Alpha
Beta
Gamma

Question 10

What is Alpha Radiation?

Answer 10

When an alpha particle is emitted from the nucleus (2 protons and neutrons)
Highly ionising and poorly penetrating
Stopped by paper

Question 11

What is Beta Radiation?

Answer 11

When an electron is emitted from the nucleus
Moderately ionising and moderately penetrating
Stopped by aluminium
For every beta particle released a neutron becomes an electron

Question 12

What is Gamma radiation?

Answer 12

When an gamma rays are emitted from the nucleus (electromagnetic waves)
Poorly ionising and highly
Stopped by concrete or lead penetrating

Question 13

What is radiation measured by?

Answer 13

Geiger-Muller tube and counter
Records the count rate (Number of radiation counts reaching it per second)

Question 14

What is half life?

Answer 14

How long it takes for the amount of radiation emitted by a source to half

Question 15

What is activity and what is it measured by?

Answer 15

Rate at which a source decays at
Measured in Becquerels (Bq)
One Bq is 1 decay per second

Question 16

Why does activity decrease overtime?

Answer 16

Each time the nucleus decays it becomes more stable

Question 17

What does a short half life mean?

Answer 17

More unstable and decay more rapidly

Question 18

What does a long half life mean?

Answer 18

Less unstable and decay less rapidly

Question 19

Natural sources of radiation

Answer 19

Food, air, building materials, rocks, cosmic rays

Question 20

Human sources of radiation

Answer 20

Nuclear explosions, nuclear waste, medical procedures (e.g. x-rays)

Question 21

What is irradiation?

Answer 21

Objects being exposed to radiation but does not become radioactive

Question 22

How to reduce the effects of irradiation

Answer 22

Keeping sources in lead-lined boxes, standing behind barriers, remote-controlled arms

Question 23

What is contamination?

Answer 23

Radioactive particles getting into objects

Question 24

How to reduce the effects of contamination

Answer 24

Gloves and tongs, protective suits

Question 25

Where is Beta and Gamma most dangerous (body)?

Answer 25

Outside the body as they can penetrate the skin and get to the delicate organs

Question 26

Where is Alpha most dangerous (body)?

Answer 26

Inside the body as they can ionise atoms and cells which can cause cancers and tumours

Question 27

Risks of using radiation

Answer 27

Ionise atoms and molecules which damages tissues Cause minor damages to cells which causes mutations (cancers) Kill cells which leads to radiation sickness (vomiting, tiredness and hair loss)

Question 28

Uses of Gamma Radiation

Answer 28

Can be injected or swallowed to see the progression of it around the body using an external detector which shows where the strongest readings are from (e.g. Iodine-123 is absorbed and can show if the Thyroid Gland is absorbing iodine as it should be) Short half-life so leaves the body quickly

Question 29

What is radiotherapy?

Answer 29

Gamma rays are directed at cancer cell without damaging normal cells, which kills the cancer

Question 30

Benefits of using radiation

Answer 30

Tracers can identify life-threatening conditions Can remove cancers entirely