You balance nuclear equations by making the sum of the superscripts and the sum of the subscripts the same on each side of the equation.
The symbol for a nucleus is
The number at the upper left is the mass number,
The number at the lower left is the atomic number,
We use special symbols for α and β particles and for protons and neutrons:
In a balanced nuclear equation, the sums of the superscripts and the sums of the subscripts must be equal on each side of the equation.
Write an equation for the decay of calcium-45 to scandium-45.
Complete the unbalanced equation.
The missing particle must have
The missing particle is
Here's a useful video on balancing nuclear equations.