Physics F5 C10

Nucleon number is the total number of protons and neutrons in a nucleus

Isotopes are atoms having the same proton number but different nucleon number

Radioisotope is an unstable isotope that will emit radioactive radiations

Alpha particle
- helium nucleus
- low penetrating power
- high ionising power
- can be stopped by a piece of paper

Beta particle
- electron
- moderate penetrating power and ionising power
- can be stopped by several mm of aluminium

Gamma ray
- electromagnetic wave
- high penetrating power
- low ionising power
- can be stopped by several cm of lead

Suitable detector - Geiger-Muller tube (G-M tube)

Half-life is the time taken for the activity of a radioactive sample to fall to half of its original value

Application of radioisotopes
- half life
--> human body - short - less dangerous to human body
--> factory - long - can be used for long time

- penetrating power
--> human body - low / medium
--> factory - medium / high

- ionising power
--> human body and factory - low

- state of material
--> solid - easy to handle
--> liquid - easy to dissolve

Nuclear fission is a process of splitting of a heavy nucleus into two or more lighter nuclei

When a high speed neutron hits to a uranium nucleus, lighter nuclei and a few neutrons are produced.
The neutrons produced will hit to some other uranium nuclei to produce more fissions and more neutrons.
A chain reaction occurs when the process is continuing and self-sustaining
The chain reaction process will stop when all the uranium nuclei had been split by the neutrons