Ionizing radiation is a type of radiation which is sufficiently energetic to push an electron out of the outer shell of an atom. Because of this, the atom will in total have a positive charge instead of a neutral charge, the atom will be ionized, and becomes an ion. This type of radiation cannot be seen, heard, tasted, smelled or felt.
Ionization can occur in two ways: directly or indirectly. The direct way can only occur through charged particles, such as alpha particles or beta particles. The indirect way occurs in steps. An uncharged particle or a photon (electromagnetic radiation) starts a reaction with an atom or an atomic nucleus. Charged particles originate in this reaction, which then ionize other atoms.
The energy that a photon requires in order to ionize an atom depends on the type of atom. For example, hydrogen requires a photon with an energy of 13.6 eV (one electron volt = 1.602 10-19 joule) to be ionized, meaning radiation with a frequency of about 3.28 1015Hz, which corresponds with the frequency of ultraviolet light. Other values apply to other atoms.
Ionizing radiation exists in many different shapes, namely:
- particle radiation
- electromagnetic radiation
Examples of particle radiation are: alpha radiation, beta radiation (of β− electrons en β+ positrons), neutrons, protons. Electromagnetic radiation consists of photons, depending on the frequency it is either X-radiation or gamma radiation.
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