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Radioactivity
occurs at the level of the infinitely small |
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| What
actually is an atom? If you magnify any material using the most powerful microscope, you will end up at the atomic level. Each atom consists of a central nucleus of positively charged protons and electrically neutral neutrons, surrounded by a "cloud" or "shell" of negatively charged electrons. You could compare an atom to a mini-solar system: the sun is the nucleus and the planets are the electrons that orbit around it. 
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| Some
atomic nuclei are unstable Usually atoms are stable. For an atom to be stable there must be an equilibrium between the numbers of different particles in its nucleus. In some atoms that equilibrium is disrupted. There are too many protons compared with the number of neutrons, or too many neutrons compared with the number of protons, or even too many of both – in other words there is too much energy in the nucleus. This nucleus is then described as unstable or radioactive. Materials that contain this kind of nucleus are called radioactive. |
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Unstable
nuclei have to get rid of their surplus energy Sooner or later every unstable nucleus will undergo changes in order to get rid of the excess energy. The energy is expelled in the form of particles or pure energy (electromagnetic waves). The process is known as radioactive decay. When does this happen? The exact moment can never be predicted: it happens spontaneously, suddenly. How
much energy is expelled? Energy is expelled until an equilibrium is established
in the nucleus. This can take place in several stages. The activity of
an amount of radioactive material gradually diminishes until it has virtually
disappeared. Decay continues until the unstable nucleus has become stable
and non-radioactive. |
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| The
radiation emitted by radioactive materials is ionizing The rays of the sun give off energy in the form of heat. The radiation from radioactive materials also gives off energy. When this radiation passes through matter, it collides with atoms or molecules and transfers some of its energy to them. An electron can be shut away from an atom or a molecule, or absorbed by it. In this way an electrically charged atom or molecule, an ion, comes into being. This phenomenon is called ionization. Radiation emitted by radioactive materials is called ionizing radiation, because it creates ionization by contact with the matter. What
is the difference between the rays of the sun and ionizing radiation?
The rays of the sun give off relatively little energy. Ionizing radiation,
on the other hand, emits so much energy that it can alter the structure
of the matter into which it penetrates. You do not find what you are looking for? Ask your questions or give us your remarks. |
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