Question #3c657

1 Answer

No. Mass number is protons and neutrons, while atomic number is only protons.


Mass number is the total mass of the atom, including protons and neutrons. They both have a mass of approximately #1# atomic mass unit, so an atom with #6# protons and #6# neutrons has a mass number of #12#. Electrons have negligible (almost zero) mass, so aren't counted.

Atomic number is only the number of protons, ignoring neutrons and electrons. Normally atoms have the same number of electrons and protons, but when bonded or ionised, the number of electrons changes, while protons stay the same.