Topic 4 - Atomic structure

Question 1

Explain the 3 types of radiation

Answer 1

Alpha - 2 protons, 2 neutrons (like a helium). Don’t penetrate very far. Strongly ionising
Beta - fast moving electron. -1 charge. moderately ionising and penetrating. For every one emitted - a neutron turns into a proton.
Gamma - EM radiation, penetrate far. weakly ionising. Absorbed by lead or concrete.

Question 2

How do alpha and beta decay affect the mass and charge of the nucleus

Answer 2

Alpha - The atomic mass decreases by 4 and the proton number decreases by 2
Beta - A proton is added changing the element and emitting an electron.

Question 3

What is the half life?

Answer 3

The time it takes for the radioactive nuclei to halve.

Question 4

How do you work out the final activity as a percentage after a certain amount of half lives

Answer 4

Find the activity after each half life then divide the final activity by the initial and multiply by 100

Question 5

Name 3 things background radiation comes from

Answer 5

natural unstable isotopes, from space (e.g. the sun), human activity - nuclear explosions.

Question 6

Explain nuclear fission and fusion

Answer 6

Fission - release energy from atoms by splitting them up

Fusion - joining two light atoms to make a heavier one

Question 7

Explain how nuclear fission and fusion work

Answer 7

Fission - The atom is split into two similar sized atoms and two or three neutrons are released. These neutrons may cause a chain reaction.
Fusion - The atomic mass and proton numbers are combined to form the new atom and radiation is released.

Question 8

How can gamma radiation be used? Explain two

Answer 8

Medical tracers - The patient is injected with the radiation which can be tracked around the body. This can detect where the problems are.
Radiotherapy - treating cancer, targeted at cancer cells to kill them. Does damage to normal cells.