What happens to the atomic number of an atom when an alpha particle is emitted?

a.) It increases by one.
b.) It decreases by two.
c.) It increases by two.
d.) It decreases by four.
e.) It decreases by one.

Question

What happens to the atomic number of an atom when an alpha particle is emitted?
 	
a.) It increases by one.
b.) It decreases by two.
c.) It increases by two.
d.) It decreases by four.
e.) It decreases by one.

anonymous · Answer

b.) It decreases by two.

The atomic number is the number of protons in the nucleus of an atom. 

When alpha-decay occurs, two neutrons and two protons are emitted from the nucleus.

Therefore, the atomic number of the nucleus reduces by two