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Some isotopes are unstable and undergo radioactive decay. They emit a variety of particles, the four most important of which are shown in the table below. When a radioactive particle is emitted, the nucleus can change into a new nucleus. This kind of change does not happen in a normal lab, because we don't usually use radioactive chemicals. But it can happen, and in fact, happens within our own bodies all the time because a small fraction of the elements that make us up are radioactive isotopes. Some people think that many cancers, and even aging, are caused by the natural radioactivity of our bodies. |
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Particle Name |
Symbol(s) |
Description |
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alpha particle |
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This is simply a helium nucleus |
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beta particle |
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This is an electron. Its mass is not zero, but it is so small that it is considered to be zero. |
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gamma particle |
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This is a massless, chargeless particle, a form of what is known as electromagnetic radiation. It is like an x-ray, except that it is more dangerous. It is unique among these because it is pure energy and is not matter. |
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positron |
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This is a positron, a positively charged "anti-electron". It is an example of antimatter. If it collides with an ordinary electron, the two particles annihilate each other giving off two x-rays (matter is transformed completely into energy) |
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Note that the first symbol is the preferred usage for each particle |
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This page was last modified on Thu, August 08, 2002 04:04 PM