v A radioactive element is an element that has very large atoms whose nucleus has many protons and neutrons.
v Because the atoms are so large, the nucleus is unstable and protons and neutrons can escape very easily.
v When a nucleus decays, large amounts of energy are released.
v These escaping protons and neutrons are called radiation.
v As the nucleus of the atom loses protons and neutrons, its atomic number changes and it becomes a different atom.
v Elements that lose protons and neutrons easily are called radioactive elements.
v Radioactive elements are found in nature.
v However, scientists have also learned how to split the nucleus of an atom by bombarding it with neutrons. This reaction is called nuclear fission.
v Nuclear fission is like a chain reaction: neutrons are used to split a nucleus that releases particles and energy. These particles then collide with other nuclei.
v An uncontrolled nuclear chain reaction produces a nuclear bomb.
v Nuclear energy can be both helpful and harmful.
Ø HELPFUL – nuclear reactors provide energy that is used to produce electricity.
Ø HELPFUL – reactors are used to make radioactive forms of many elements. These elements are used in medical research and in the treatment of certain illnesses.
Ø HARMFUL – radiation can pass through human tissues, damaging cells along the way which can cause serious illness or death.
© Ellen Gabor, 2005