Soddy And Fajans Displacement Law

Several Scientists have all together studied the process of radioactive decay, and various laws governing the same have been given in this context. One such famous law about radioactive decay was given by Soddy and Fajan. The law was given by Frederick Soddy, and Kazimierz Fajan collectively is also known as the ‘radioactive displacement law.’

Frederick Soddy’s and Kazimierz Fajans Law

The law regarding radioactive decay was studied by two scientists, Frederick Soddy and Kazimierz Fajan.

Since we all know that it was Rutherford who described the phenomenon of radioactive decay, the transmutation of elements during the radioactive decay process was only discovered by the work done by Frederick Soddy and Kazimierz Fajan.

The law of radioactive displacement, commonly known as ‘Soddy’s –  Fajan’s Displacement Law,’ can be stated as the radioactive element, and the isotope that occurs in each radioactive decay is different for different types of decay. This interchanging of one element to another was called ‘Transmutation of Elements.’

Before going into details regarding the law, it’s important to understand the work of Frederick Soddy and Kazimierz Fajan, how they came forward to work on the radioactive decay, and the details regarding the term ‘Transmutation of Elements.’

Frederick Soddy

On September 2, 1877, Frederick Soddy was born in Eastbourne, Sussex, London. He got his primary education at Eastbourne College and studied at the University College of Wales, Aberystwyth.

He was awarded a scholarship at Oxford University in 1895, and after two years of research at Oxford University, he later went to Canada to McGill University. At McGill University, he met professor Sir Ernest Rutherford.

As Sir Ernest Rutherford was busy working on the radioactive elements, Frederick Soddy too showed interest in his work, and they both published many papers on the same.

They, through their works and findings, concluded that radioactive emission leads to the formation of new particles that happen during the decay of a radioactive element. When a radioactive element decays, many new elements arise from the decay.

This was an important discovery because it helped scientists to understand the concept of alpha decay, beta decay, and gamma decay.

After leaving McGill University, Frederick later went to University College, London, and worked with Sir William Ramsay. There he was able to demonstrate through his spectroscopic work that helium was found to be produced during the radioactive decay of Helium.

He took a sample of radioactive bromide and concluded the same.

After doing much of the practical work on radioactivity, he came up with a simple ‘Displacement Law’ which stated that during radioactive decay two protons and two neutrons are emitted from an element which is called an alpha particle. Therefore the atomic number of the element is decreased by 2 and atomic mass number is decreased by 4. Thus, the element moves back two positions in the Periodic Table.

Kazimierz Fajan

Kazimierz Fajan was born on May 2 in 1887 in Warsaw, Poland.

Kazimierz Fajan started working at the Oxford laboratory where Sir Ernest Rutherford was already working on the radioactive elements.

When Fajan started working with Rutherford, his prime research was based on radioactive rows. He was the first one to discover the half-lives of uranium and actinium, and thorium nuclides.

Afterward, he started working on the electrochemical properties of radioactive elements. He noticed the radioactive shifts in the radioactive decays of the particles, which were further stated as ‘Soddy’s – Fajans  Displacement Law’ as both of their work was the same.

Transmutation of the elements

The transmutation of the elements is the process that occurs when an element changes from one state to another. So, when the transmutation of elements occurs, the particles change into isotopes and can go back into their original state.

In radioactivity, this transmutation of the elements leads to the formation of the particles such as a

alpha particles, gamma particles, and beta particles.

In radioactivity, alpha, beta, and gamma decay commonly occur when a radioactive element breaks down during the bombardment.

State Soddy – Fajans Displacement Law 

As we know that during radioactive decay, some particles bombard into different forms. Fajans displacement law also states the same. Soddy and Fajan’s finding was later clubbed together to what the radioactive and nuclear physics says or state Soddy-Fajans Displacement Law.

It was studied by both scientists that when a nuclear particle disintegrates, it breaks into many particles. This was termed a transmutation of particles, and isotopes were also discovered during this study. Moreover, it was found that when alpha decay happens, the atomic number gets reduced by 2, and the mass number also gets reduced by 4 of that of the parent radioisotope taken.

In beta decay, there is. However, no change observed in the mass number of the element atomic number increases by 1.

Conclusion : 

Soddy’s-Fajans displacement law helped study radioactivity and the associated phenomenon. It also helped to study the isotopes.