Radioactivity is a natural phenomenon

Radioactive materials seek equilibrium just as water finds its own level.

Radioactivity was discovered by Henri Bequerel
in 1896.

The attempts of the nucleus to reach eqilibrium, give rise to radioactivity.

Radioactivity is associated with atomic bombs or hazards of nuclear power stations...

..but its also associated with the treatment of cancer and other beneficial functions.

Nuclear energy and nuclear medicine have developed from research into radioactivity.

Radioactivity is useful but can be dangerous.

Radiation is all around us.
We call this background radiation.

Radon gas from rocks and cosmic rays from outer space contribute to background radiation.

Background radiation usually amounts to between 20 and 50 counts per minute.

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
.....the development of nuclear energy with all its potential and hazards
.....the development of nuclear medicine which has greatly improved diagnosis and treatment techniques.

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.

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