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Nature of radioactivity, types of radiation Interaction radiation with matter Radiation sources, natural and artificial radiation  Radiation detection Health effects of radiation  Regulation, legal basis Nuclear and radiological accidents, protection measures Frequently Asked Questions

Radioactivity is a phenomenon of radioactive decay of the nucleus. Radioactive decay is the ability of some nucleus to be spontaneously transformed into another nucleus or into the same nucleus with less energy. The extra energy is released by emitting particles (alpha, beta, gamma, neutron or others). Atom structure All materials are composed of atoms. An atom consists of a positive charged nucleus and negatively charged electrons, enclosing it. The atom has no electronic charge.  In 1911 Ernest Rutherford showed that mass of the atoms was mainly concentrated (99.9%) in the nucleus. The size of an atom approximately equals to 10^-10 m . The size of the nucleus is in order of 10^-15 ч 10^- 14 m. The charge of one electron equals to 1.6x10^-19 Coulomb (C) or in relative units to –1. The charge of the nucleus Z is positive and equal in relative units to serial number of current chemical element in Periodic table of elements. Charge of nucleus equal to number of protons in nucleus. Number of protons and neutrons in nucleus called atomic mass number A. more >>