What is radioactivity?
Radioactivity is the spontaneous emission of radiation from certain
substances with the consequent transformation of that substance into a
different substance. An example of a radioactive material is the
element, Uranium which spontaneously emits radiation and in the process,
individual atoms of the Uranium sample turn into atoms of Thorium.
| Different kinds of radiation are emitted randomly and spontaneously from radioactive materials like Uranium. |
When was it discovered?
Radioactivity has been around as long as the Universe, but scientists
only discovered it by accident in 1896. Without radioactivity stars
would not shine and the ingredients from which we are built never could
have been formed.
Why is it important?
Radioactivity is important because of its many uses and also because it
can be dangerous. It is also important because scientific exploration of
radioactivity has led to....
| .....a new and deeper understanding of the atom which was critical to the advances in technology over the last hundred years |
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| .....the development of nuclear energy with all its potential and hazards |
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| .....the development of nuclear medicine which has greatly improved diagnosis and treatment techniques. |
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Radioactive materials
Although the majority of elements are stable, about a dozen have been
found to be unstable. These unstable ones decay with the emission of
radiation. The decay takes the form of individual atoms releasing
radiation and in the process, changing character in an attempt to reach
a more stable condition.
Transformation
The emission of radiation from a radioactive material leaves behind
atoms that have been transformed in a quest for a more stable condition.
Often these transformed atoms are themselves unstable and emit radiation
and are further transformed on route to a stable condition.
Natural & Artificial Radioactivity
Radioactivity is a natural phenomenon that is taking place all around us
all the time. Since energy is released by radioactivity, scientists were
keen to harness it and to find new ways to obtain it. This led to the
discovery of artificial radioactivity where normally stable elements
were bombarded with high speed particles to make them radioactive and
consequently emit energy.
There are many factors that contribute to natural radioactivity. Radon gas is an example of a naturally occuring substance that is radioactive. We refer to the radiation present in our environment as background radiation.In most cases this represents an acceptable level of radiation exposure. A higher level of radiation than the background level may be a cause for concern.When investigating emissions from a radioactive source, first establish the background count and subtract this from subsequent readings.
How does radioactivity occur?
How radioactivity occurs and how stable atoms can be made radioactive are explained in the Theory section of this site. However you may wish to learn first about how radioactivity was discovered
What is cosmic radiation?
Cosmic rays are charged particles moving at nearly the speed of light reaching the earth from outer space.
More Information
Radioactivity general
Radioactivity overview
Radioactivity explained