4. Isotopes, Radioactive Isotopes Atoms of the same element that have different numbers of neutrons are called isotopes. If an atom is unstable , the nucleus can decay and give off radiation – these are called radioactive isotopes. Carbon-14 is a radioactive isotope that is found in all living things. Scientists can determine how old an object is by determining how much Carbon 14 is in the object.
![Atoms, Elements, Compounds ,[object Object],The nucleus is at the center of the atom. Positively charged particles called protons and particles with no charge called neutrons are located in the nucleus. Electrons with negative charges are located outside the nucleus. Atoms contain an equal amount of protons and electrons and have a total charge of zero.](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)