In some elements, the nucleus can split as a result of absorbing an additional neutron, through a process called nuclear fission. When radioisotopes are used in medicine or industry, it is vital to know how rapidly they lose their radioactivity, in order to know the precise amount of radioisotope that is available for the medical procedure or industrial use. This time can range from fractions of a second (for radon-220) to millions of years (for thorium-232). Essentially, a half-life of a radioactive material is the time it takes one-half of the atoms of a radioisotope to decay by emitting radiation. This gradual loss of radioactivity is measured in half-lives. Through this process - called radioactive decay - radioisotopes lose their radioactivity over time. This radiation can be emitted in the form of positively charged alpha particles, negatively charged beta particles, gamma rays, or x-rays, as explained below. This less-familiar form of radiation includes alpha particles, beta particles, and neutrons, as explained below.Īs previously indicated, large unstable atoms become more stable by emitting radiation to get rid of excess atomic energy ( radioactivity). The other form of radiation - known as particle radiation - is tiny fast-moving particles that have both energy and mass (weight). Familiar types of electromagnetic radiation include sunlight ( cosmic radiation), x-rays, radar, and radio waves. This form of radiation - known as electromagnetic radiation - is like vibrating or pulsating rays or "waves" of electrical and magnetic energy. One form of radiation is pure energy with no weight. In that process, unstable nuclei may emit a quantity of energy, and this spontaneous emission is what we call radiation.įor additional information, see the following topics on this page:Īs previously indicated, matter gives off energy (radiation) in two basic physical forms. These forces within the atom work toward a strong, stable balance by getting rid of excess atomic energy ( radioactivity). The nucleus carries a positive electrical charge, while the electrons carry a negative electrical charge. Atoms are made up of various parts the nucleus contains minute particles called protons and neutrons, and the atom's outer shell contains other particles called electrons. The water evaporates into steam which turns a turbine, which in turn drives a generator to produce electricity.Radiation is energy given off by matter in the form of rays or high-speed particles. The kinetic energy of the neutrons is harnessed by the nuclear reactor and used to heat water. The reactor is covered with a thick concrete shield to ensure that no radiation is able to penetrate through and escape the reactor. To stop this happening, the reactor contains control rods, usually made of boron, which absorb some of the extra neutrons so that only a single neutrons is released per fission event. It is important that the chain reaction doesn’t get out of hand, otherwise the reactor could explode. These neutrons hit other nuclei in a chain reaction. When a neutron is absorbed by a nucleus, it undergoes a fission event, breaking apart into two nuclei and two or three neutrons. Fission only works if the neutron is moving slowly enough to be absorbed by a nucleus so nuclear reactors contain something called a moderator, usually made of graphite, which reduces the speed of the neutrons, making them more likely to be absorbed by a nucleus. Fission is used in nuclear reactors to produce energy.
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