Nuclear Energy

5. a nuclear reaction in which a heavy nucleus splits spontaneously or on impact with another particle, with the release of energy.
6. the total number of protons and neutrons in a nucleus.
9. a fast-moving electron emitted by radioactive decay of substances.
10. 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.
12. a chemical reaction or other process in which the products themselves promote or spread the reaction, which under certain conditions may accelerate dramatically.
13. a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.

1. gamma rays.
2. a helium nucleus emitted by some radioactive substances, originally regarded as a ray.
3. the central and most important part of an object, movement, or group, forming the basis for its activity and growth.
4. the time taken for the radioactivity of a specified isotope to fall to half its original value.
7. 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.
8. the emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei.
11. a stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron
14. 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.