Transmutation in Nuclear Chemistry

Transmutation Definition 

It is derived from the Latin word ‘transmutare’ which means "to change from one form into another". In general, transmutation is any transformation from one form or species into another. (transmute meaning is to change from one form or substance into another). In Chemistry, Transmutation is a process in which the nucleus changes in the number of protons to produce an atom with a different atomic number. It can be done artificially or can occur naturally.  

Radioactive decay, nuclear fission, and nuclear fusion can be termed as natural processes by which one element is transformed into another. The first artificial transmutation was done by Lord Rutherford in the year 1911. He bombarded alpha particles on Nitrogen-14 to produce Oxygen-17 with protons. 

¹⁴₇N  + ⁴₂He  → ¹⁷₈O + ¹₁H 

Here, the total number of protons is 9 and the total mass is 18 on both sides.

Fission and Fusion Reactions

There are two types of nuclear reactions called nuclear fission and nuclear fusion. In the case of nuclear fission, an atom disintegrates into two or lighter atoms on the other hand nuclear fusion occurs when two or more atoms combine or fuse together to form a large or heavy atom.

Nuclear Fission: 

The word fission means splitting. Nuclear fission takes place when an unstable isotope (atoms with the same number of protons but a different number of neutrons) is bombarded by high-speed particles, usually neutrons. This splits the nucleus and breaks it down into two smaller isotopes (the fission products) along with three high-speed neutrons, with a release of a large amount of energy. They are used in nuclear power reactors to produce large amounts of energy. 

Eg: when a uranium-235 atom is bombarded with a neutron, the heavy nucleus of the uranium splits and produces krypton-94 and barium-139 with the emission of three neutrons and a large amount of energy.

Nuclear Fusion: 

The word fusion means " merging of separate elements into a whole". Nuclear fusion means the "union of atomic nuclei to form heavier nuclei resulting in the release of enormous amounts of energy". The energy released in this process is greater than the nuclear fission reaction. 

Eg: The fusion process occurs in the sun where the atoms of Hydrogen (isotopes: Hydrogen-3, and Hydrogen-2) Deuterium and Tritium combine in a huge pressure atmosphere with extremely high temperatures to form a neutron and an isotope of Helium.

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Transmutation Reactions

Transmutation of species or elements results in the formation of new elements from radioactive elements with the emission of radiation like alpha, beta or gamma rays. Natural transmutations are spontaneous in-process and usually occur with unstable radioactive elements. The series of chain reactions result in the formation of stable elements. On the other hand, artificial transmutation occurs in nuclear reactors with the bombardment of particles like neutrons.

²²⁸₈₈ Ra  →  ⁴₂ He  +  ²¹⁸₈₆ Rn

¹³¹₅₃ I  →  ¹³¹₅₄ Xe + ⁰₋₁ e

²²₁₁ Na  →  ²²₁₀ Ne  +  ⁰₋₁ e   

The equations can be balanced by using simple rules. The mass number of reactants and product sides must be conserved in a nuclear change. If there is more than one reactant or product, the sum of the mass numbers must remain the same before and after the reaction. Similarly, the electric charge must be conserved in any transmutation process. Transmutation Alchemy is the conversion of base elements into precious metals (gold or silver).

Did you know?

The first observation of transmutation was done in 1901 when Frederick Soddy and Ernest Rutherford observed thorium changing into radium via radioactive decay. According to Soddy, he exclaimed, "Rutherford, this is transmutation!" To which Rutherford replied, "For Christ's sake, Soddy, don't call it transmutation. They'll have our heads off as alchemists!"