79. Nuclear Decay Equations

Nuclear equations are used to represent what happens to an atom's nucleus during radioactive decay. In any nuclear equation, the total mass and atomic numbers must be the same on both sides of the arrow.

1. Alpha Decay (\alpha )

An alpha particle is a helium nucleus ( _2^4 He), consisting of 2 protons and 2 neutrons.

• Mass Number: Decreases by 4.

• Atomic Number: Decreases by 2.

• Example: Uranium-238 decaying into Thorium-234.

  ^{238}_{92}\text{U} \rightarrow ^{234}_{90}\text{Th} + ^4_2\text{He}

2. Beta Decay (\beta )

In beta decay, a neutron turns into a proton and emits a fast-moving electron (_{-1}^0e).

• Mass Number: Stays the same (it loses a neutron but gains a proton).

• Atomic Number: Increases by 1.

• Example: Carbon-14 decaying into Nitrogen-14.

  ^{14}_{6}\text{C} \rightarrow ^{14}_{7}\text{N} + ^0_{-1}e

3. Gamma Decay (\gamma )

Gamma radiation is an electromagnetic wave ( _0^0 \gamma ) with no mass or charge.

• Mass Number: Stays the same.

• Atomic Number: Stays the same.

• Result: The element does not change; it just loses excess energy.

  ^{234}_{90}\text{Th} \rightarrow ^{234}_{90}\text{Th} + ^0_{0}\gamma

4. Neutron Emission (n)

The nucleus simply "throws out" a neutron (_0^1n).

• Mass Number: Decreases by 1.

• Atomic Number: Stays the same.

• Example: Beryllium-9 decaying into Beryllium-8.

  ^{9}_{4}\text{Be} \rightarrow ^{8}_{4}\text{Be} + ^1_{0}n

Summary Table