Linda Levy, age 13, of Rochester, P?.Y., for her question:
What is a radioactive object?
Radioactivity goes on in the cores of certain atoms: The heart or core of an atom is its nucleus, and this nucleus is a tightly bound bundle of assorted atomic particles. An atom may lose, gain or swap the electron particles which orbit the nucleus and the atoms themselves do not change. But, when an atom loses a particle from its nucleus, it becomes an atom of something else.
Under normal conditions, the particles in the nucleus cannot be disturbed. Radioactivity is an unusual event in which the particles in the atomic nucleus break apart. There are certain radioactive substances in nature in which large, heavy atoms are steadily breaking down into smaller atoms. One of these radioactive substances is uranium,
The particles in the nucleus are bound together with tremendous energy. When one or more of these particles breaks away, some of this nuclear energy is released. A radioactive substance is forever giving off radioactive energy. This radioactivity pours forth in streams of energy. Two of these streams or rays are made from high speed atomic particles. The most powerful ray is electromagnetic energy, somewhat like X ray only much more powerful.
The weakest ray pouring from a radioactive object is made of alpha particles. These particles are like the nucleus of the helium atom, which has two positively charged protons and two neutrons. They may travel at 18,600 miles a second but they become worn out after traveling for a few inches through the air. They can be stopped by a few sheets of paper.
The beta ray is a stream of high speed electrons. This stream of radioactive energy can pierce 200 times deeper than the alpha ray. Any electron is a single charge of negative electricity which has only 1/1845th the mass of a proton. Small as they are, these electrons pour from a radioactive object at the speed of light, 186, 000 miles a second. A thick wad of cardboard or a thin sheet of aluminum will stop the beta rap.
The third stream of energy pouring forth from a radioactive object is the gamma ray. This ray is charged with neither positive nor negative electricity. It pours forth like X ray and travels with the speed of light. The gamma ray can pass deep into solid substances. It can be stopped by several inches of lead or by about a foot of iron. All three of these rays plunge into the flesh when we touch a radioactive object arid the gamma rays can reach us from quite a distance. This is why the hospital keeps its supply of precious radioactive radium in a lead prison