To understand ionizing radiation, it is important to understand how nuclear reactions work.
What is an atom?
- The atom is the basic building block of the chemical elements that form matter. An atom is a collection of protons, neutrons and electrons. Together, protons and neutrons form the atomic nucleus. The nucleus is very small, holds a positive charge and contains almost all of the mass of the atom. Light, negative-charged particles called electrons orbit around the nucleus. Each atom has an equal number of electrons and protons, making it electrically neutral.
- All matter in the universe is made up of countless combinations of the approximately 100 elements that exist in nature. The atoms of each element differ only in the number of particles they contain. Atoms are about 0.1 millionths of a millimetre in size. The nucleus itself is 10,000 times smaller.
What is radioactivity?
- Radioactivity is a phenomenon caused by certain unstable atomic nuclei spontaneously disintegrating into new, lighter and more stable nuclei. It is accompanied by a release of energy in the form of one or more types of radiation: alpha, beta or gamma. The radioactive elements (uranium, thorium, potassium) in the Earth’s core are disintegrating, heating it from the inside and causing earthquakes and volcanoes.
What is natural radiation?
Radioactivity is a natural phenomenon that we are exposed to daily. It comes from many sources, both natural and artificial, that emit radiation of varying intensity.
Natural sources, particularly stars such as the Sun, are responsible for over two-thirds of the ionizing radiation to which we are exposed. Naturally radioactive substances in soil, such as potassium and uranium, and in materials like granite and brick, also produce radiation. Even the human body is radioactive because of the potassium it contains.
What is ionizing radiation?
- Radioactive nuclei liberate excess energy through radiation, in the form of helium nuclei (alpha radiation), electrons (beta radiation) or light particles or photons (X-rays or gamma radiation). This type of radiation carries a great deal of energy and ionizes any matter it encounters, moving electrons around the way a bowling ball transmits its energy to the pins it knocks over.
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