The name radioactivity implies that it is the act of emitting radiation in a spontaneous way. Ample amount of neutrons in a nucleus results in emission of negative beta particles whereas excessive amounts of proton results in emission of positrons. Let us learn in detail.

The word Radioactivity comes from the combination of two words, radiationem, which is the Latin word for “a shining” and actif, which is the French for “active.” Radioactivity is the process where radiation takes place spontaneously from the unstable nucleus of elements. This process was first identified by the French Physicist, Henri Becquerel in 1896 in a salt of Uranium. Two years later, in 1898, Pierre Curie and Mary Curie introduced the world to Polonium and Radium, the two other naturally occurring radioactive elements. Radioactivity has since been used by science for a variety of purposes which includes its use for chemotherapy for treating cancer, in diagnostics like X-Ray, MRI and Radiography and also for Geology and Archaeology. 

The concept of radioactivity 

The entire function of radioactivity is being operated by an atomic nucleus with the aim to release some energy by which it can shift towards a sustainable configuration. In physics, it indicates the process through which any nucleus of any unstable atom loses its energy by the way of ionising radiation. Each nucleus integrates to find the most favourable configuration. The eminent scientist Marie Curie first coined the word “radioactivity”. The history tells that the Curies had extracted Uranium from ore and after a certain period and without their concern, they noticed the amount was reduced. More suspiciously, the remaining ore was more reactive in nature compared to the pure uranium. 

After a prolonged time of research, it has been confirmed that alpha, beta and gamma particles are the responsible factors for decaying the original ore. In this way, radioactivity comes in the experimental periphery and in the present era it is broadly elaborated for explaining carbon dating. 

How to measure radioactivity 

From the core context of the radioactivity measurement process, it has been determined that the ultimate radiation has been generated by the major “disintegration of the radioisotopes” which can easily interact with the matter and it has been activated in the forms of transferring energy. On the other hand, the proper magnitude and the entire gravity of the significant effects could rely on the preliminary dose and the factual kind of received radiation. Additionally, “Geiger counters” have been commonly used to compute the whole amount of the radioactivity. However, there are many other kinds of valid detectors which can be useful to measure the radioactivity. Hence, Radioactivity has been critically measured or checked in “disintegrations per second” and its overall measurement unit is called the “Becquerel (Bq)”.

Definition of radioactive half-life 

Half life refers to the time period or the rate that a radioactive isotope takes to decay. However, half life period greatly vary among the different types of atom. The below mentioned formula is used to measure half life period of a radioactive particle. 


Here t1/2 refers to the half life period of the radioactive particle, λ denotes the constant.  If n be the size of any radioactive atom at a given time period of t, then dN depicts the amount by which it decreases in time dT. Hence, the rate of change can be expressed as 

N/dt = -λN

Here λ can be considered as a decay constant. 

Decay chain 

In nuclear science, the radioactive decay chain depicts the series of radioactive decay and different radioactive decay results in different sequences of transformation. In other words it is termed as a radioactive cascade. In many cases, atoms earn satiability in just one decay or a nucleus might obtain a series to complete its decaying process. For example, a decay chain that starts with Uranium 238 within Lead 206, it can form several intermediates such as “Uranium-234”, “Thorium-230”, “Radium-226” and “Radon-222”. Hence, it can be called a decay series or decay chain. 

Radio activity can be caused artificially 

Neutron activation is the classic example of artificially induced radioactivity and it is considered as the basic concept behind the formation of atom bomb. Here the process of radiation is used to make or convert the previously stable material into a radioactive material. Radioactivity can be stated as a physical phenomenon. It can be measured from the biological aspect. One can measure radioactivity based on the counts of atoms which are released in each second. The nature of radioactive emission can be divided into four distinct groups: Alpha decay, Beta minus decay, Gamma Decay and isomeric transition. 

Radioactive elements in the periodic table 

There are 38 elements which are radioactive in the periodic table. Among 89, Actinium (Ac) and 103, lawrencium (Lr), uranium (U) and Thorium (Th) are natural. Lr and Th have existence on earth. Promethium (Pm), Americium (Am), Lutetium (Lu), Cerium (Cu) are the radioactive elements in the Lanthanide series in the periodic table. On the other hand, most of the radioactive elements like Plutonium (Pu), Neptunium (Np), Nobelium (No) etc are in the Actinide series in the periodic table.


Thus, it can be concluded that radioactivity can occur through natural processes. Apart from it, it can also be caused through human intervention. Neutron activation can be considered as an artificial radioactivity. For cancer patients boron solution can be injected. In simple physics, the treatment is controversial and complex also and it is still experimental.