Group+2+P-6+Average+Atomic+Mass

=Average Atomic Mass=

__**Definition**__ - weighted mean of the atomic masses of all the atoms of a chemical found in a particular substance weighted by isotopic substance. Each answer is labeled in atomic mass units (amu's).


 * __Class Notes:__**
 * Lecture Slides and Videos - October 14, 2010

__**Questions**__ 1. What is the purpose of finding the average atomic mass? - The purpose is to find the weighted average of all of the atoms of a chemical element.

2. Copper is used in electric wires comes in two isotopes: Cu-63 and Cu-65. C-63 has an abundance of 69.09%. Cu-65 has an abundance of 30.91% What is the average atomic mass of Copper? - You can find this out by :

__65x30.91% + 63x69.09%__ = **63.182 amus** .. . . . ..... 100

3. If Rb-85 and Rb-87 have an average atomic mass of 85.556 amus and Rb-87 has an abundance of 27.8% then what is the unknown abundance of Rb-85?

100-27.8 = 72.2% .............. The abundance is 72.2%

__**Equation**__

(Atomic Mass x Abundance) + (Atomic Mass x Abundance) ........................................ 100


 * Divide by 100 to get ride of the percents.

LINKS:
__**Further Practice**__
 * [|Average Atomic Mass Practice #1]
 * [[file:Average Atomic Mass Practice #2.pdf]]
 * __[|Solutions to Average Atomic Mass Worksheet]__
 * This was homework the week of October 14, 2010

by Chelsea Brennan, Samantha Atamian, Aubrey Postolakis, and Megan Ruiz