Why some elements possess fractional atomic mass?

Answer 1

It is mostly because elements have many isotopes and their average comes to be also fractional.We cannot weigh the atom therefore its Atomic Mass is fractional.Even elements with only 1 naturally occurring isotope have fractional mass. This is because the nuclear binding energy is a very large (negative) energy, and it shows up in the atomic mass because of the relativistic adjustment that has to be made --

E= mc2

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Answer 2

1. First cause: the atomic weight is the sum of the weights of protons, neutrons ans electrons.; they don't have masses as integers.

2. Second cause: also occurs the so-called mass defect.

Not atomic mass for elements; atomic weight is correct.

Answer 3

That's because all samples of elements have Isotopes ( Isotopes are atoms of the same element with the same atomic number) and atomic mass is calculated as the average of atomic masses of all the Isotopes for each element.

Answer 4

Elements can exist as different isotopes, atoms with the same proton number but different neutron number. Their atomic masses are therefore an average, based on the number of isotopes, their respective weight and relative abundance.

Answer 5

Because some of the elements masses have the same isotopes inside the atom that is similar to their amount of protons.