Radioactivity

Question 1

What is the atomic (Proton) number?

Answer 1

Number of protons in a nucleus

Question 2

What is mass (nucleon) number?

Answer 2

Number of proton and neutrons in a nucleus

Question 3

3 types of radiation are…

Answer 3

Alpha and beta particles
Gamma radiation

Question 4

What makes a nucleus unstable?

Answer 4

More neutrons than protons

Question 5

What word describes the way a radioisotope decays?

Answer 5

Random

Question 6

All types of radiation are capable of ….

Answer 6

Ionisation

Question 7

Describe alpha particles..

Answer 7

2 proton 2 neutrons
helium nucleus
highly ionising
low penetrating power
stopped by 5cm of air or paper

Question 8

Describe beta particles …

Answer 8

Very fast electron
medium ionising power
medium penetrating power
stopped by mm of aluminium

Question 9

Describe gamma….

Answer 9

very high frequency electromagnetic radiation
low ionising power
high penetrating power
stopped by thick lead or metres of concrete

Question 10

Why is alpha highly ionising?

Answer 10

large mass
2+ charge

Question 11

What do you use to detect radiation?

Answer 11

GM tube and counter
photographic film

Question 12

Sources of background radiation…

Answer 12

cosmic rays
rocks
food
nuclear waste

Question 13

Unit of activity is …

Answer 13

Becquerels (Bq)

Question 14

Define half life

Answer 14

Time taken for half the radioactive nuclei to decay.
Time taken for activity to fall by half

Question 15

In an experiment to measure activity, how do you deal with background radiation?

Answer 15

measure background before and after the experiment, take a average and subtract it from all readings

Question 16

Uses of radioactivity

Answer 16

treating cancer
sterilising medical equipment
medical tracers
industry tracers
dating articles

Question 17

What is the difference between contamination and radiation?

Answer 17

Contamination: radioactive material enters the body
Irradiation: radiation passed through

Question 18

Dangers of radiation

Answer 18

mutations in living organisms
damage cells and tissues
problems with disposing of radioactive waste

Question 19

What is fission?

Answer 19

Neutron splits a heavy, unstable nuclei, producing 2 daughter nuclei and more neutrons, releasing energy

Question 20

What is fusion?

Answer 20

Two light nuclei join to make one heaver one and release Kinetic energy. Energy comes from a loss of mass during fusion

Question 21

2 conditions needs for fusion

Answer 21

high temps
high pressure

Question 22

What is a chain reaction?

Answer 22

Each fission produces more neutrons which go on to split more nuclei and numbers and energy released build up very quickly

Question 23

What are control rods?

Answer 23

Used in a nuclear fission reactor to absorb excess neutrons and limit fission

Question 24

What is a moderator?

Answer 24

Slows down neutrons so they can be absorbed by the nuclei to split it

Question 25

What is shielding?

Answer 25

Outer layer of thick concrete and lead to ensure radiation in contained in a nuclear reactor

Question 26

Where does fusion happen naturally?

Answer 26

in the stars

Question 27

Why can’t fusion happen at low temps and pressures?

Answer 27

Nuclei are positively charged and so would repel due to electrostatic repulsion