# Question #e6de5

Oct 25, 2016

In nature, copper appears in many different isotopes. These isotopes appear in many different frequencies and masses.

#### Explanation:

On the periodic table, the value given for copper represents the weighted average of all the masses of all the isotopes of copper. In this instance, there are 2 isotopes of copper: ${_}^{63} C U$ and ${_}^{65} C U$. ^63CU appeares in nature at a frequency of 69.17%, and ^65CU appears at frequency of 30.83%. To find the mass given on the periodic table, you do this: (mass of an isotope * percentage in decimal form) + (mass of an isotope * percentage in decimal form), adding any more you need. In this instance, it should look like this:

$\left(62.93 \cdot 0.6917\right) + \left(64.93 \cdot 0.3083\right)$

$43.5287 + 20.0719$

$63.546$ amu