How do you figure out a alpha decay of a mass number and atomic number.

Question

1.) A monoatomic atom or ion with 52 protons, 50 neutrons, and 50 electrons undergoes an alpha decay. What is its mass number after the alpha decay?

2.) A monoatomic atom or ion with 66 protons, 60 neutrons, and 63 electrons undergoes an alpha decay. What is its atomic number after the alpha decay?

Answer 1

In alpha decay, the atom loses 2 protons and 2 neutrons (aka, a helium nucleus).

1) What was 52 protons is now 50 protons. What was 50 neutrons is now 48 neutrons. So the mass number (neutrons + protons) is 48 + 50 = 98

2) What was 66 protons is now 64 protons. What was 60 neutrons is now 58 neutrons. So the mass number (neutrons + protons) is 58 + 64 = 122