Introduction

The nuclei of an atom exhibit the phenomenon of radioactivity due to nuclear instability. The nucleus of an unstable atom loses energy by producing radiation. Henry Becquerel observed this occurrence in 1896. 

A little amount of Uranium compound was wrapped in black paper and put in a drawer containing photographic plates. After further examination of these plates, it was discovered that there had been an exposure. This phenomenon is called Radioactive Decay. Elements or isotopes that emit radiation and undergo radioactivity are radioactive. Let’s take a closer look at the radioactive decay law in these notes.

What is the Radioactive Decay Law?

The spontaneous decay of an unstable atomic nucleus into an atomic nucleus to generate a more energetically stable atomic nucleus is radioactivity. When a small mass is turned into energy, radioactive decay is a random and extremely stochastic first-order process. 

Types of Radioactive Decay

There are three types of radioactive decay:

• Alpha Decay
• Beta Decay
• Gamma Decay

Alpha Decay

Alpha decay is a form of radioactive decay in which some unstable atomic nuclei spontaneously release an alpha particle to dissipate excess energy. Because alpha particles have two positive charges and a mass of four units, their emission from the nucleus results in a daughter nucleus with a positive nuclear charge and an atomic number of two units less than the parent’s mass and mass. As a result, Po-210 (mass number 210 and atomic number 84, i.e. 84 protons ) decays to Pb-206 through alpha emission (atomic number 82). 

Beta Decay

A proton is turned into a neutron or vice versa inside the nucleus of a radioactive sample in beta decay. The nucleus of a radioactive sample can get as close to the ideal neutron/proton ratio as is feasible through processes like beta decay and alpha decay. The nucleus emits a beta particle, which can be either an electron or a positron while doing so. Remember that a proton can become a neutron, or a neutron can become a proton. To obey the law of charge conservation, electrons and positrons are created. The weak interaction causes beta decay.

Gamma Decay

Gamma decay is the release of excess energy to stabilise an unstable nucleus by emitting electromagnetic radiation with a very high frequency or very high energy. It might be well-versed in the various energy levels found in an atom. The nucleus has its own set of energy levels to work with. 

Gamma decay is the nucleus’ method of transitioning from a higher to a lower energy level by emitting high-energy photons. The atom’s energy level transition energies are measured in MeV. As a result, emitted gamma rays, like X-rays, have very high energy of order MeV.

Radioactive decay law

Radioactive decay is impossible to forecast due to the nucleus’s smaller size than the atom and the magnitude of the electromagnetic force. The atomic nucleus is located in the centre of the atom, which is shielded from the environment by surrounding electrons. As a result, the study of the element’s environment-independent degradation. 

In other words, the rate of decay is independent of an element’s physical state, such as temperature and pressure. The rate of decay or disintegration of a specific element is proportional to the number of atoms present, and activity is measured in atoms per unit of time. If “A” denotes the rate of disintegration and “N” denotes the number of radioactive atoms, then the direct relationship is as follows.

A∝N

A= λN (mathematical representation)

A represents the no. of decays per unit time of a radioactive sample

N represents the total number of particles in the sample

 λ is the constant of proportionality or decays constantly

Conclusion

In the above notes, we have learnt about the radioactive decay law and types of Radioactive Decay. The loss of elementary particles from an unstable nucleus causes radioactive decay, transforming the unstable material into a more stable element. Alpha emission, beta emission, positron emission, electron capture, and gamma emission are the five kinds of radioactive decay. Each form of decay emits a distinct particle, which alters the end product. The decay or emission that the initial element undergoes determines the number of protons and neutrons found in the daughter nuclei.