radioactive decay of rocks

4. activity the process by which nuclei emit particles and rays
5. radiation, radiation with enough energy to knock electrons off some atoms of a bombarded substance to produce ions
7. dating used to date rocks that formed from about 1 million years to over 4.5 billion years ago by studying the properties of radioactive Uranium-238
9. the conversion on an atom of one element to an atom of another element
12. the time required for one-half of the nuclei of a radioisotope sample to decay to products
13. the splitting of a nucleus into smaller fragments, accompanied by the release of neutrons and a large amount of energy
14. dating a method of determining the age of an object containing organic material by using the properties of carbon-14, a radioactive isotope of carbon; used to date objects up to 50,000 years old

1. an isotope that has an unstable nucleus and undergoes radioactive decay
2. elements, any elements in the periodic with atomic number above 92, the atomic number of uranium
3. counter a device that uses a gas-filled metal tube to detect radiation
6. ray a high-energy photon emitted by a radioisotope; most damaging form of radiation to living cells
8. the penetrating rays and particles emitted by a radioactive source
10. particle a positively charged particle emitted from certain radioactive nuclei
11. the process of combining nuclei to produce a nucleus of greater mass
15. particle an electron resulting from the breaking apart of neutrons in an atom