How does radium differ from uranium?
Uranium and radium are radioactive substances. Their unstable atoms are steadily breaking into smaller atoms, giving off nuclear radiation as they do so. Heavy uranium atoms start an orderly breakdown into smaller and smaller atoms. At one stage, the process produces a number of radium atoms. Radioactive uranium is the ancestor of a number of radioactive descendants. The last of the family tree is a form of lead and this lead isotope is non-radioactive. It takes 4 1/2 billion years for a certain number of uranium atoms to become these stable atoms that end the long chain of radioactive decay. In the meantime, the uranium atoms become different isotopes and other atoms, each one smaller than its parent. The breakdowns occur at a fixed date and radium atoms are formed at one stage of the radioactive decay from uranium to lead. The core of an atom is the tight fisted assorted particles in its nucleus. The nature of an atom depends upon the number of positively charged protons in its nucle
