The weighted average of the atomic masses of the naturally occuring isotopes of an element is the A) atomic mass of the element
B) atomic number of the element
C) mass number of each isotope
D) formula mass of each isotope

The weighted average of the atomic masses of the naturally occurring isotopes of an element is the : A) atomic mass of the element.

Isotopes can be defined as two or more forms of a chemical element that contains equal number of protons (atomic number) and electrons but different number of neutrons.

The isotope of any chemical element is denoted by

Where;  

In Chemistry, the atomic mass of a chemical element is weighted average of the atomic masses of the naturally occurring isotopes and its units is u.

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The weighted average of the atomic masses of the naturally occurring isotopes of an element is the

A) atomic mass of the element

Isotopes are elements that have the same Atomic Number (Proton)

Atomic mass is the average atomic mass of all its isotopes

So  Isotopes have the same atomic number(the same number of protons and electrons), but different mass numbers (different neutron numbers)

Avg atomic mass = m1.%m1 + m2.%m2mn.%mn

m1 = isotope 1

m2 = isotope 2

% = abundance of the elements in nature