Copper has two stable isotopes 63cu and 65cu. 63cu has an abundance of 69.09%. the other isotope, 65cu, has an abundance of 30.91%. calculate the average atomic mass of copper.
If 63 and 65 are the atomic masses of the two copper isotopes, then 63x69.09=4352.67 and 65x30.91=2009.15 and adding, 4352.678+2009.15=6361.82/100= 63.62 would be the average atomic weight of copper.
