CP+4-+Average+Atomic+Mass+Group+5

//Average atomic mass// is the mass of an isotope multiplied by its relative abundance over 100.


 * How to Solve for the Average Atomic Mass & Set Up an Equation:**

Example: Uranium has three common isotopes. If the abundance of 234U is 0.01%, the abundance of 235U is 0.71%, and the abundance of 238U is 99.28%, what is the average atomic mass of Uranium?

Step 1: Take the mass of the isotope and multiply it by the relative abundance. Then, divide by 100 because of the percent. __(.01 x 234) + (.71 x 235) + (99.28 x 238)__ 100

Step 2: Solve. __2.34 + 166.85 +23628.64__ = The average atomic mass of Uranium is 237.9783 amu’s 100


 * Sample Questions:**

1) What is the difference between atomic mass and the average atomic mass?

The atomic mass is of one element while the average atomic mass is the average of two or more elements.

2) What is the average atomic mass of three isotopes of Magnesium (Mg) if the abundance of 24Mg is 78.99%, the abundance of 25Mg is 10%, and the abundance of 26Mg is 11.01%?

(24 x 78.99) + (25 x 10) + (26 x 11.01) --- 100  =  24.3202

Created by Christina Michelle Giovanni, Joanne Cojo Suh, Krista Muska, and Cassie Beck.