What is an element atomic mass?

Answer 1

Atomic mass is the number of protons in an atom's nucleus. Since all atoms are, in their natural state, neutral, there are the same number of electrons as protons. Thus, the atomic mass tells you both the number of electrons and protons an atom has.

No, this answer is incorrect. Atomic mass is the number of protons plus neutrons. Only the number of protons is equal to the number of electrons in a neutral atom; so knowing the atomic mass doesn't tell you the number of electrons, because you don't know the combination of protons and neutrons that were added together to get the atomic mass.

Answer 2

The Atomic Mass of an element is the average mass of the isotopes of that element, taking into account their relative abundances. It is expressed in atomic mass units (u) and can be found on the Periodic Table underneath the elemental symbol.

Answer 3

The mass is the total number of subatomic particles: protons, electrons, and neutrons. The reason it is often a decimal is that the number on the table is the average for the most common isotopes. Isotopes are atoms of an element with different numbers of neutrons.