Respuesta :

Answer:

They aren't listed as a whole number, because an atom's mass is not always a whole number. The mass differs between types of atoms as well.

Answer:

This is because atoms ionize, isotopes exist, and the fact that their are impurities.

Explanation:

Each atomic mass could not be calculated accurately if it was a whole number.

- Hope this helped! Please let me know if you need further explanation.