Nuclear Reactions – Full Explanation

Nuclear reactions involve changes in the nucleus of an atom. Unlike chemical reactions that deal with electrons and release limited energy, nuclear reactions transform elements and produce massive energy, either absorbed or released.

Why Are Nuclear Reactions Unique?

They change the structure of the atomic nucleus — protons and neutrons are rearranged.
New elements or isotopes form through a process called transmutation.
They release energy millions of times greater than chemical reactions.
These reactions occur naturally (like in radioactive decay) or artificially (in labs and reactors).

Major Types of Nuclear Reactions

1. Nuclear Fission

In nuclear fission, a heavy atomic nucleus like Uranium-235 splits into two smaller nuclei, releasing neutrons and vast energy.

Example: U-235 + neutron → Ba-141 + Kr-92 + 3 neutrons + energy

Used in power plants to generate electricity.
Chain reactions are managed with control rods and moderators.
Uncontrolled fission causes atomic explosions.

2. Nuclear Fusion

Fusion combines two light nuclei, often hydrogen isotopes, into a heavier nucleus. This process powers stars, including our sun.

Example: ²H + ³H → ⁴He + neutron + energy

Produces more energy than fission.
Requires extreme temperatures (millions of °C).
Considered a future clean energy source; research continues in fusion reactors.

3. Radioactive Decay

In radioactive decay, unstable nuclei release radiation to become more stable. This natural process helps us understand atomic behavior.

Alpha (α) decay: Releases a helium nucleus.
Beta (β) decay: Converts a neutron to a proton (β⁻) or vice versa (β⁺).
Gamma (γ) decay: Emits high-energy electromagnetic radiation, often after α or β decay.

These forms of decay are useful in medicine, archaeology, and industry.

4. Artificial Transmutation

Scientists create new elements or isotopes by bombarding nuclei with high-energy particles like neutrons or protons.

Essential for producing radioactive isotopes in medicine and industry.
Enabled the discovery of synthetic elements beyond uranium (transuranic elements).

How to Write Nuclear Reaction Equations

Nuclear reactions use symbolic equations to show the transformation from reactants to products.

Example:₉₃Np²³⁹ + ₂He⁴ → ₉₅Am²⁴² + ₀n¹

Practical Applications of Nuclear Reactions

Power generation: Nuclear reactors generate electricity using fission.
Medical technologies: Radiation therapy, PET scans, and tracers in diagnostics.
Scientific discovery: Used in physics research and space science.
Carbon dating: Determines the age of archaeological and geological samples.
Weapons: Both atomic and hydrogen bombs rely on nuclear reactions.
Space travel: Radioisotope thermoelectric generators (RTGs) power space probes.

Key Concepts to Remember

Mass defect: Mass converts to energy (E = mc²) in nuclear reactions.
Energy is typically measured in MeV (Mega electron volts).
Nuclear reactions can turn one element into another.
The neutron-to-proton ratio impacts nuclear stability.

✅ Nuclear reactions drive clean energy, medical breakthroughs, and our understanding of matter and the universe.