# Zinc has five naturally occurring isotopes 48.63% of ^(64)Zn, with an atomic weight of 63.929...

## Question:

Zinc has five naturally occurring isotopes 48.63% of {eq}^{64}Zn {/eq}, with an atomic weight of 63.929 amu; 27.90% of {eq}^{66}Zn {/eq} with an atomic weight of 65.926 amu; 4.10% of {eq}^{67}Zn {/eq} with an atomic weight of 66.927 amu; 18.75% of {eq}^{68}Zn {/eq}, with an atomic weight of 67.925 amu; and 0.62% of {eq}^{70}Zn {/eq} with an atomic weight of 69.925.

Calculate the average atomic weight of Zn.

## Isotopes and average atomic mass:

Isotopes are forms of the same element with different atomic mass. This is due to the atom having the same number of protons, but different number of neutrons. The average of atomic mass of an element is the summation of all the atomic weights of the element's isotopes multiplied to their corresponding percent natural abundance.

{eq}ave. \ atomic \ mass = \dfrac{\sum(mass \ of \ isotopes \times \ \% \ natural \ abundance)}{100}{/eq}

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Using the equation, plug-in the values to calculate for the average atomic mass of Zinc.

{eq}\begin{align*} Zn_{ave. \ atomic \ mass} &=...

Isotopes and Average Atomic Mass

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Chapter 2 / Lesson 3
54K

Understand the definition of atomic mass, atomic number, and atomic weight. Discover how to find atomic mass, and learn what an atomic number represents.