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An atom is said to be unstable if the forces acting between the particles constituting the nucleus are unbalanced. In other terms, if the nucleus has excess internal energy, the atom is termed as an unstable atom or radioactive.
Nucleus is composed of neutrons (neutral particles) and protons (positive charged particles). The instability of an atom is due to unbalanced forces between these particles or excess of either neutrons or protons. Therefore, due to this instability, atoms will make an attempt to become stable or achieve stable configuration by ejecting nucleons (combination of neutrons and protons) or releasing energy in different forms. Hence, it is not a biological but a physical phenomenon.
Radioactivity
Radioactivity is defined as the phenomenon of emission of the radiation continuously due to the continuous disintegration of the nucleus of an atom. This action of releasing the radiation is due to instability of an atom, therefore it tends to move into the stable configuration. Consider a giant ball made up of tiny magnets spinning at a fast pace. In such a case, some pieces of magnet might shoot out from the ball and hit the wall. This example could be considered somehow as how radiation looks like.
Cause of Radioactivity
In nature, there are atoms of different materials. Some of them are stable and some unstable.
For an atom to be stable, the forces acting between particles constituting the nucleus should be balanced. If there is excess of either neutrons or protons, the atom will be unstable. To become stable, the nucleus will eject the nucleons. If the number of neutrons is greater in the nucleus, the nucleus will give out a negative beta particle, resulting in a change of a single neutron within a proton and if the number of protons is greater in the nucleus, the nucleus gives out a positron (particle that is positively charged), turning a proton to the neutron. Also, too much mass of the nucleus will lead to emitting an alpha particle by discarding the heavy particles ( two protons and two neutrons). Also, such a large amount of energy in the nucleus will give out a gamma ray, which rejects large energy without replacing any particle in the nucleus.
As the nucleus emits the radiation or disintegrates, the radioactive atom turns into a different nuclide. This process is known as radioactive decay. It will continue until the forces between the particles of the nucleus get balanced.
For example: if an unstable atom decays, it will become the isotopes of the same atom by emitting a neutron or will become an atom of another element by emitting protons. The characteristics of radionuclide is denoted by the series of transformations that a nuclide goes to achieve stability and the type of radiation produced.
Difference between Radioactivity and Radiation
Radiation can be defined as the energy or the particles emitted during radioactive decay. Meanwhile, the radioactivity of an atom can be defined as the rate at which the emission of radiation takes place from the nucleus. Every disintegration takes place as emission of energy or particles takes place.
1 disintegration per second is equal to 1 becquerel.
Types of nuclear radiation
Based the nature of the decaying effect of the nucleus, there are three types of radiation particles:
1.Alpha particle (α): Alpha particles are composed of 2 protons and 2 neutrons (helium nucleus). Many atoms often decay by emitting an alpha particle. They are larger than the other two types and are positively charged. However, alpha particles can cause a lot of damage.
2.Beta particle (β): Beta particles are produced when there is a decay of a neutron to a proton. Beta particles are in the form of electrons that possess high energy. The penetrating power of beta particles is higher than alpha particles. Most beta particles can be stopped using a small aluminium plate.
3.Gamma rays (γ): Gamma rays are radiation of a much higher frequency. These radiations possess no charge and have a considerably high penetrating power (greater than beta particles). Gamma rays are the photons emitted from the nucleus.
Conclusion
The property of radioactivity is shown by certain types of matter emitting radiation continuously. Henry Becquerel first noticed the phenomenon of radioactivity in 1896. The unstable atoms emitted the radiation to achieve a stable configuration. Hence, radioactivity is not a biological phenomenon but a physical phenomenon.
