P7 (radiation)

Question 1

Ionising radiation

Answer 1

Pulls electrons away from atoms and causes mutations in DNA/DNA to break apart.

Question 2

Name the three types of radiation

Answer 2

Alpha, beta and gamma

Question 3

What is radiation

Answer 3

Particles or waves that are emitted from atoms

Question 4

Alpha particle make-up

Example of emitting an alpha particle

Answer 4

a (2 protons, 2 neutrons)
238 234 4
Th produces Ra +. a
90. 80. 2
(Thorium (Th) is unstable so produces radium and an alpha particle

Question 5

Describe Rutherford’s gold foil experiment

Answer 5

A radioactive source emitted positively charged alpha particles towards thin gold foil. Most went through the foil however some scattered into different directions (if they hit a nucleus)

Question 6

What conclusions did Rutherford make after his gold foil experiment ? (6)

Answer 6

An atom is mostly space
Most of the mass of an atom is located in the centre
The nucleus is positive
Electrons orbit the nucleus and they are at least 10,000 times smaller than the atom
This is the NUCLEAR MODEL

Question 7

What is an isotope

Answer 7

The same element (same protons) but a different number of neutrons

Question 8

What happens in beta decay

Answer 8

The radioactive isotope has an unstable amount of neutrons. A neutron turns into a proton and emits a fast moving electron (B particle)

Question 9

How is a beta particle written

Answer 9

0
B
-1

Question 10

What is gamma radiation and how does it differ to beta and alpha

Answer 10

Gamma radiation emits and electromagnetic wave from the nucleus. Both beta and gamma emit particles but gamma emits and electromagnetic wave. Also a gamma wave has no mass and no charge.

Question 11

Alpha radiation

• charge
• mass
• what could it penetrate
• range in air

Answer 11

• charge is +2
• mass is four protons
• it will be absorbed by paper
• range in air is 5cm

Question 12

Beta radiation

• charge
• mass
• could penetrate
• range in air

Answer 12

• charge is -1
• mass is 1/2000th of a proton
• will pass through skin but is absorbed by a few cm thick aluminium
• range in air is 1m

Question 13

Gamma radiation

• charge
• mass
• will penetrate
• range in air

Answer 13

• no charge
• no mass
• absorbed by a thick lead sheet or concrete
• range in air is unlimited

Question 14

Irradiation

Answer 14

When an object is exposed to ionising radiation

Question 15

Radioactive contamination

Answer 15

Radioactive contamination is the presence of radioactive substances on surfaces,solids,liquids or gases when their presence is unintended

Question 16

How to protect yourself from radiation

Answer 16

Use a respirator, have a radiation detector and use time and distance shielding

Question 17

How is alpha radiation useful and how does that work

Answer 17

Found in smoke alarms
Alpha radiation ionises the air and this allows a current to flow between two electrodes. Alpha is weakly penetrative so smoke stops its current, the current drops and this sets the alarm off.

Question 18

Which type of radiation is most dangerous in the body

Answer 18

Alpha radiation because it is charged (so ionising),can’t leave your body but can easily penetrate your cells causing mutation, alpha decay and possible cancer.