Question

question:
why is the average atomic mass on the periodic table often a decimal instead of a whole number?

because it is a weighted average of all naturally occurring isotopes

because electrons are included in the total

because isotopes have fractional protons

because neutrons are sometimes shared between atoms

Explanation:

• Option 1: Average atomic mass is a weighted average of the masses of all naturally occurring isotopes of an element, considering their relative abundances. This weighted average can result in a decimal.
• Option 2: Electrons have negligible mass compared to protons and neutrons, so including them doesn't significantly affect the atomic mass to make it a decimal.
• Option 3: Isotopes have the same number of protons (only neutrons differ), so they don't have fractional protons.
• Option 4: Neutrons are not shared between atoms in a way that would affect atomic mass calculation for the periodic table.

Answer:

A. Because it is a weighted average of all naturally occurring isotopes