The longer the half-life of a substance the slower the substance will decay and the less radiation it will emit in a certain length of time.
The following radioactive substances contain 1000 unstable atoms. Click on the up and down buttons get to the number of unstable atoms remaining after the length of time shown.
Here are the main uses you will be expected to know about: 1.
Uses in medicine to kill cancer - radiation damages or kills cells, which can cause cancer, but it can also be used to kill cancerous cells inside the body.
Radioactive substances will give out radiation all the time, regardless of what happens to them physically or chemically.
Materials that originally came from living things, such as wood and natural fibres, can be dated by measuring the amount of carbon-14 they contain.
By plotting a graph of count-rate against time the half-life can be seen on the graph.
This would also work if you plotted the number of parent atoms against time.
We cannot predict exactly which atom will decay at a certain time but we can estimate, using the half-life, how many will decay over a period of time.
The half-life of a substance can be found by measuring the count-rate of the substance with a Geiger-Muller tube over a period of time.