# Why must nuclear equations must be balanced?

##### 1 Answer

Nuclear equations must be balanced because they must obey the law of conservation of mass and the law of conservation of charge.

In a nuclear symbol such as

The 2 is the mass number — the number of protons and neutrons.

That means that the sum of all the subscripts (charges) and of all the superscripts (masses) must be the same on each side of the equation.

Let's see how this works in some typical nuclear reactions.

**α Decay**

**β⁻ Decay**

**β⁺ Decay**

**Fission**

**Fusion**

In all cases, the sum of the subscripts (charges) and the sum of the superscripts (masses) is the same on each side of the equation.