Question

the average atomic mass of an element is never an integer. there are two reasons. what are they?

Answer 1

1) The very first reason why atomic mass of an element is not an integer is because it is the weighted average of a number if naturally occurring isotopes of that particular element. the average is not likely to be an integer.

2) The mass of an atom isn't simply the adding up the masses of its individual protons, neutrons and electrons. This may seem incorrect, but the cause is the binding energy which is required to hold the atom together. This energy must comes from somewhere (due to stability) and is equal to E = mc². Because energy is required to hold the nucleus together in all atoms except ¹H, a small loss of mass (the m in the equation) occurs and it is not a whole number therefore.