Atomic mass: What is Atomic Mass

What is Atomic Mass ? Atomic mass , sometimes referred to as atomic weight, is just an average of the different masses of an element. This number usually has units of amu or u. The atomic mass of one isotope of an element is the sum of that isotopes subatomic particles: protons, neutrons, and electrons (usually of negligible mass .) Learn what atomic mass is, how it is measured and how it differs from molecular mass . Find out the atomic mass of some elements and how to calculate the molecular mass of compounds. Atomic mass in an atom or group of an atom is the sum of the masses of protons, neutrons and electrons. The electrons have very less mass in comparison to protons or neutrons so the mass of electrons is not influenced in the calculation. For an element, relative atomic mass is the average mass of the naturally occurring isotopes of that element relative to the mass of an atom of 12C. Which means one atom is given a relative atomic mass of exactly 12. Atomic mass is not reported with units ... The atomic mass (relative isotopic mass) is defined as the mass of a single atom, which can only be one isotope (nuclide) at a time, and is not an abundance-weighted average, as in the case of relative atomic mass /atomic weight.