Unit 2: Radioactive decay

Question 1

Why do atoms decay

Answer 1

The larger the atoms the more neutrons it needs for protons. atoms decay to become more stable

Question 2

Radioactive decay is ____ but _____

Answer 2

Random but predictable

Question 3

What is alpha radiation made up of and what is the RM RC

Answer 3

A particle - 2 protons 2 neutrons RM 4 RC 2

Question 4

What is beta radiation made up of and what is the RM RC

Answer 4

B particle- proton converted to neutron and high-speed electron ejected RM 0.0005 RC-1

Question 5

What is gamma radiation made up of and what is the RM RC

Answer 5

G radiation is made up of photons and has 0 RM RC

Question 6

What is the most to least penetrative

Answer 6

A 2+4= 6 Least penatrative
B 1+0.0005=1.0005
g 0 most penatrative

Question 7

What is a use of alpha radiation

Answer 7

Americium 241- smoke detector- ionises air so current can flow in a circuit. smoke fills the chamber and current doesn’t flow. safe to use as it doesn’t penetrate out of the smoke detector

Rolling out a sheet of paper to uniform thickness- alpha emitter and detector. more or less detection correlates to thickness

Question 8

What is a use of beta radiation

Answer 8

Iridium 192- abnormalities in surface or paint application will show up on radiation camera as a build-up
leaks in pipes could be detected on camera

Question 9

What are uses of gamma radiation

Answer 9

Technetium 99m (metastable)- see where it is absorbed and detect abnormalities in absorption. different chemical forms are used for different body parts

Question 10

What is half life

Answer 10

Exponential decay- the time needed for half of the radioactive material to decay.

Question 11

Decay calculations

Answer 11

lambda- decay constant decays per unit time
a- activity decays per unit time 
Bq- decays per second
T1/2- half-life
N- number of undecayed nuclei
N0- initial number of nuclei