Write a balanced nuclear equation for the alpha decay of americium-241

When you say alpha decay, it means that the reaction would yield alpha particles. An alpha particle, α, is like helium; it has 2 protons and 4 as its mass number. So, the balanced nuclear reaction is:

Let the first number written after the element symbol be the superscript and the number after the comma be the subscript.

Am241,95 - - > α4,2 + Np237,93