Part D: Compare and contrast the properties of elements and their radioactive isotopes

Radioactive isotope or radioisotope, natural or artificially created isotope of a chemical element having an unstable nucleus that decays, emitting alpha, beta, or gamma rays until stability is reached. Isotopes are two forms of an element with the same atomic number but different mass number. Isotopes can be looked at by analyzing the structure of atoms. There are three kind of simple particles an atom contains: Protons, neutrons, and electrons. Only Hydrogen is an exception to the sentence above because it doesn't contain neutrons. Protons and neutrons are in the nucleus and the electrons are outside of the nucleus in electron clouds. The way you tell the difference between atoms is the number of protons in the nucleus. The number of protons in the nucleus is called the atomic number of the atom. The atomic mass of an atom is the number of neutrons and protons combined. So if an atom had 3 neutrons and 3 protons it would have a mass number of 6. Most elements have at least two stable isotopes. The term stable here means not radioactive.

Radioactive isotopes
A radioactive isotope is an isotope that spontaneously breaks apart, changing into some other isotope. As an example, potassium has a radioactive isotope with mass number 40, 40K or potassium-40. This isotope breaks down into a stable isotope of potassium, 39K or potassium-39.
Radioactive isotopes are much more common than are stable isotopes. At least 1,000 radioactive isotopes occur in nature or have been produced synthetically in particle accelerators (atom-smashers) or nuclear reactors (devices used to control the release of energy from nuclear reactions).

(Advameg Inc., 2008)