n. 1  The charter that King John of England issued in 1215 at the behest of his barons, recognizing the right of persons to certain basic liberties, such as due process, later also embodied in the American Constitution: We are heirs to a tradition given voice 800 years ago by Magna Carta, which ...
Radioactive decay occurs in unstable atomic nuclei â that is, ones that donât have enough binding energy to hold the nucleus together due to an excess of either protons or neutrons. It comes in three main types â named alpha, beta and gamma for the first three letters of the Greek alphabet.Alpha decay.fter a nucleus undergoes alpha or beta decay, it is often left in an excited state with excess energy. Just as an electron can move to a lower energy state by emitting a photon somewhere in the ultraviolet to infrared range, an atomic nucleus loses energy by emitting a gamma ray.
radioactive isotope, also called radioisotope, any of several species of the same chemical element with different masses whose nuclei are unstable and dissipate excess energy â¦ by spontaneously emitting radiation in the form of alpha, beta, and gamma rays. Every chemical element has one or more radioactive isotopes.For example, hydrogen, the lightest element, has three isotopes with mass numbers 1, 2, and 3. Only hydrogen-3 (tritium), however, is a radioactive isotope, the other two being stable. More than 1,000 radioactive isotopes of the various elements are known.adioactive isotope, also called radioisotope, any of several species of the same chemical element with different masses whose nuclei are unstable and dissipate excess energy â¦ by spontaneously emitting radiation in the form of alpha, beta, and gamma rays. Every chemical element has one or more radioactive isotopes.