Nuclear energy

2. a chemical reaction or other process in which the products themselves promote or spread the reaction, which under certain conditions may accelerate dramatically.
4. the total number of protons and neutrons in a nucleus.
7. a nuclear reaction in which a heavy nucleus splits spontaneously or on impact with another particle, with the release of energy.
8. a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.
10. a fast-moving electron emitted by radioactive decay of substances. (The emission of beta particles was originally regarded as a ray.).
13. gamma rays.
14. each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

1. The emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei.
3. a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen.
5. the energy released during nuclear fission or fusion, especially when used to generate electricity.
6. he time required for any specified property (e.g. the concentration of a substance in the body) to decrease by half.
9. a helium nucleus emitted by some radioactive substances, originally regarded as a ray.
11. the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.
12. a stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign