radioactivity

1. a tube and counter that records all the alpha, beta, and gamma decay that reaches them
5. neutrally charged. Relative mass 1.
8. when radioactive particles get onto other objects
10. the emission of energy in the form of ionizing radiation
12. measurement. means decay per second. one of these = 1 decay per second
13. an element with the same number of protons but different number of neutrons. Some of these have unstable nuclei which causes it to radiate.

2. the process by which objects are exposed to radiation
3. negatively charged. Relative mass 1/2000.
4. a type of radiation which emits a particle with 2 protons and 2 neutrons, often represented with helium atom. highly ionising, weakly penetrating.
6. a type of radiation that emits waves of electromagnetic radiation. weakly ionising as passes through material, highly penetrating
7. a type of radiation that occurs when one of an atom's neutrons decays into a proton and electron. proton stays in nucleus, electron emitted at highspeed. moderately ionising and penetrating.
9. time it takes for half a radioactive sample to decay
11. positively charged. Relative mass 1 Its amount determines type of element