Radiation

1. Energy carried by particles from a radioactive substance, or spreading out from a source.
6. Most ionising and the least penetrative type of radiation
7. The types of radiation that is used to measure the thickness of paper
8. Most penetrative and the least ionising type of radiation
10. An uncharged atom or molecule into a charged particle by adding or removing electrons
11. A substance is contaminated if another substance is mixed or dispersed within it.
12. The experiment which discovered a positively charged nucleus
13. Low level nuclear radiation that is always present from natural and man-made sources

2. Atoms of an element with the same number of protons and electrons but different numbers of neutrons
3. The scientific idea that an atom is a sphere of positive charge, with negatively charged electrons in it.
4. When unstable atoms give off particles that can be harmful to humans.
5. Highest source of nuclear radiation that is always present from natural and man-made sources
9. Process of exposing an object to a source of radiation. Eg fruit exposed to gamma rays in order to destroy bacteria is said to have been irradiated.