P6 - Radioactivity

Question 1

What are the 3 types of radiation ?

Answer 1

• alpha
• beta
• gamma

Question 2

What are the properties of alpha ?

Answer 2

Helium nucleus- 2 protons, 2 neutrons
- Highly ionising
- Is stopped by paper
- Can only travel a few cm in air

Question 2

What are the properties of beta ?

Answer 2

• A fast moving electron
• Is stopped by aluminium
• Lower ionising then alpha
• Travel very fast

Question 3

What are the properties of gamma ?

Answer 3

• A EM wave
• Can pass through everything but lead
• Lowest ionising power

Question 4

How do you detect radiation ?

Answer 4

Using a Geiger counter

Question 5

What happens during alpha decay ?

Answer 5

• An alpha particle is emitted from the unstable nucleus
• A completely new element is formed in the process

Question 6

What happens during beta decay ?

Answer 6

• A neutron turns into a proton and electron
• The electron is emitted and the proton stays in the nucleus

Question 7

What happens during gamma decay ?

Answer 7

A gamma ray is emitted from an unstable nucleus

Question 8

What is half life ?

Answer 8

The time it takes for the number of nuclei of a sample of radioactive isotopes to decrease by half

Question 9

How do you calculate the half life of a substance ?

Answer 9

Measure the initial activity, A0, of the sample

Determine the half-life of this original activity

Measure how the activity changes with time

The time taken for the activity to decrease to half its original value is the half-life

Half-life can be shown clearly on a graph

Question 10

What is irradiation ?

Answer 10

The process of exposing a material to alpha, beta or gamma radiation

Irradiating a material does not make that material radioactive

Question 11

What is contamination ?

Answer 11

Contamination is where small amounts of the radioactive isotope leak onto the material

The only way a material can become radioactive is if that material becomes contaminated