What is the #"mass number"# of an atom?

1 Answer

#"The mass number of an atom............."#

Explanation:

The mass number of an atom is its #"atomic number,"# #Z#, PLUS its number of neutrons.....i.e. it is the number of massive nuclear particles. The mass number is specific to a particular isotope. Can you tell me the mass numbers of the following hydrogen isotopes: #""^1H#, #""^2H#, and #""^3H#?