Aquatic Pollution and Coastal Management

Unit 10 : Radioactive pollution

10.2.Nature of Radioactivity
The nucleus of an atom contains nucleons, which are either positively charged proton or electrically neutral neutrons bound together by powerful nuclear forces which enable to overcome the electrostatic repulsion between the protons.
The cloud of electrons surrounds the nucleus, which revolves around the nucleus, each of which carries negative charges equal to the positive charges on protons and hence the charge on the nucleus, determines the element to which the atom belongs and its chemical properties. An atom commonly loses or gains one or more electrons in the course of the chemical reaction or through physical process. Then it becomes positively or negatively charged ion and its chemically much reactive then the electrostatically neutral atom. The process by which this occurs is ionization.
The atoms of the same chemical element have the same number of protons in the nucleus, but the number of neutron may vary. These variants are known as isotopes.
Example: 99% of naturally occurring carbon has nucleus containing 6 protons and 6 neutrons and is designated carbon – 12 or C12 because its nucleus contains 12 nucleons but 1% contains 7 neutrons and is designated carbon-13, Both of these are stable isotopes, but some other isotopes are unstable. Potassium with 19 protons and 20 neutrons as Potassium 39 and Potassium 40 with 19 protons and 21 neutrons occur naturally as unstable isotopes.
The instability of the nucleus is set right by a change in the ratio of protons to neutrons accompanied by the emission of particles and energy. This is known as radioactivity and the unstable forms are radioisotopes or radionuclides.