Natural vs Artificial Radioactivity
Radioactivity has not been invented by man; it has been there, existing in the universe since time immemorial. But it was a chance discovery by Henry Becquerel in 1896 that the world came to know about it. Radioactivity was finally explained by Marie Curie in 1898 who also earned a Nobel Prize for her work. We refer to radioactivity taking place in the world (read stars) on its own as natural radioactivity while that which is induced by man is called artificial radioactivity. There are differences in the two processes that will be highlighted in this article.
In general, radioactivity refers to release of particles and energy from unstable nuclei. The release of particles from unstable atoms continues until the substance reaches stability. This decomposition of the nuclei is called radioactivity. When this decomposition takes place in nature, it is called natural radioactivity while when unstable nuclei are prepared in labs bombarding them with slow moving neutrons, it is called artificial radioactivity.
Uranium is the heaviest occurring natural element (atomic number 92). There are isotopes of thorium and Uranium that are radioactive but artificial radioactivity has meant that we have created a series of transuranium elements that are capable of radioactivity.
Radioactivity involves emission of three types of particles by an unstable nucleus in an effort to reach stability. These are known as alpha, beta, and gamma radiations. Alpha particles are made up of two protons and two neutrons (exactly like a helium atom) which is why it is positively charged. Alpha particles are very small fragments of the parent nucleus that tries to release energy and alpha particles in an attempt to become stable. Beta particles are made up of electrons and are therefore negatively charged. Third and final particles that are emitted by a radioactive nucleus are gamma particles that are made up of high energy photons. In fact they are nothing but pure energy without mass. Not all three radiations take place in case of an unstable nucleus at the same time.
Uranium (238) ———-Thorium (234) + He (4)
Radioactivity is made use of in nuclear reactors where slow moving neutrons are made to bombard a stable isotope of uranium that becomes unstable and starts to decay releasing a huge amount of energy that is used to turn water into steam. This steam moves turbines producing electricity. Artificial radioactivity is also made use of in atom bombs where fission of unstable nucleus results in release of huge amounts of energy and the reaction is uncontrolled whereas in nuclear reactors, the reaction is controlled.
Natural Radioactivity vs Artificial Radioactivity
• Radioactivity is a natural phenomenon that has existed in universe since its creation. It is a process of decomposition of heavy, unstable nuclei into smaller, stable nuclei with a simultaneous release of high amounts of energy.
• When radioactivity takes place on its own in nature, it is called natural radioactivity while when it is induced by man in laboratories, it is called artificial radioactivity.
• Transuranium elements, made by man are used for the purpose of artificial radioactivity.