This is the international symbol for radiation. If you see this symbol, there are probably radioactive materials nearby.
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Original artwork by Windows to the Universe staff.

Radioactive

Some materials give off radiation. We call those materials "radioactive". Radioactive materials are often dangerous to people and other living things.

There are many different kinds of radioactive materials. Some give off particle radiation, like alpha or beta particles or neutron radiation. Some give off electromagnetic radiation, such as gamma rays or X-rays.

Most elements come in different "versions", called isotopes. Some isotopes are radioactive. Other isotopes are not. Isotopes that are not radioactive are called "stable" isotopes.

Radioactive isotopes can be dangerous to living things. They can also cause damage to equipment such as electronics. Radioactive isotopes are not always dangerous, though. Some only give off tiny amounts of radiation. There are radioactive isotopes in nature all around us. Most of them cause us little or no harm.

Humans use radioactive materials in many ways. We use them in medicine to treat cancer. We use them to find out how old artifacts are with carbon-14 dating. We also use them for nuclear power and in nuclear weapons.

Last modified August 26, 2009 by Randy Russell.

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