Question

Why are all average atomic masses found as decimals?

Using your knowledge we did average explain how it is used to determine average atomic masses

Answer 1

Atomic masses are the weighted average of all the isotopes of the element; hence, the atomic mass is always in decimal form as a fractional average.

Another explanation: Is atomic mass always an average of the isotopes (so you would refer to the atomic mass of elements only), or is it used for the mass of specific isotopes.

Answer 2

Many of the atomic masses listed on the periodic table are decimal values because it's the weighted average mass of all of the isotopes of that element. The mass of each isotope of an element is multiplied by its percent abundance in nature