Nuclear Reaction: Definition, Types, Examples, Equations

– In this subject, we will discuss the Nuclear Reaction: Definition, Types, Examples, and Equations.

Nuclear Reaction

– In a chemical reaction, there is merely a rearrangement of extranuclear electrons.

– The atomic nucleus remains intact.

– A nuclear reaction involves a change in the composition of the nucleus.

– The number of protons and neutrons in the nucleus is altered.

– The product is a new nucleus of another atom with a different atomic number and/or mass number.

– Nuclear reaction: is one which proceeds with a change in the composition of the nucleus to produce an atom of a new element.

– The conversion of one element to another by a nuclear change is called Transmutation.

– We have already considered the nuclear reactions of radioactive nuclei, producing new isotopes.

– Here we will consider such reactions caused by artificial means.

Differences between Nuclear Reaction and Chemical Reaction

Nuclear Fission Reactions

– In these reactions, an atomic nucleus is broken or fissioned into two or more fragments.

– This is accomplished by bombarding an atom with alpha particles (⁴He₂ ), neutrons (¹n₀), protons (¹H₁), deuterons (²H₁), etc.

– All the positively charged particles are accelerated to high kinetic energies by a device such as a cyclotron.

– This does not apply to electrically neutral neutrons.

– The projectile enters the nucleus and produces an unstable ‘compound nucleus’.

– It decomposes instantaneously to give the products.

– For example, ¹⁴N₇ when struck by an α-particle first forms an intermediate unstable compound nucleus, ¹⁸F₉, which at once cleaves to form stables ¹⁷O₈

– Other examples are:

– Nuclear fission reactions are classified according to the projectile used and the particle that is emitted.

– In the Figure above the type of the reaction has been stated.

– It is noteworthy that neutrons are particularly useful as the projectile.

– Sir James Chadwick obtained these by bombarding beryllium-9 with α-particles.

– Being electrically neutral, neutrons pierce the positive nucleus easily.

Nuclear Fusion Reactions

– These reactions take place by combination or fusion of two small nuclei into a larger nucleus.

– At extremely high temperatures the kinetic energy of these nuclei overweighs the electrical repulsions between them.

– Thus they coalesce to give an unstable mass which decomposes to give a stable large nucleus and a small particle as the proton, neutron, positron, etc.

– For example :

(1) Two hydrogen nuclei, ¹H₁, fuse to produce a deuterium nucleus, ²H₁.

(2) Deuterium nucleus, ²H₁, and tritium nucleus, ³H₁ , combine to give helium nucleus, ⁴He₂ with the expulsion of a neutron.

Differences between Nuclear Fission and Nuclear Fusion

Reference: Essentials of Physical Chemistry /Arun Bahl, B.S Bahl and G.D. Tuli / multicolor edition.