Copper has two isotopes, copper-63 and copper-65. The relative abun-
dance of copper-63 is 69.1% and copper-65, 30.9%. Calculate the
average atomic mass of copper.

63.55 amu

Explanation:

(0.692 * 62.930) + (0.308 * 64.928) = 63.55 amu

Copper has two naturally occurring

isotopes: copper-63 (69.17%) and

copper-65 (30.83%).

Calculate the average atomic mass of

copper if the relative masses of the

isotope are copper 63 (62.93 amu)

and copper-65 (64.93 amu).

Cu-63 (0.6917 x 62.93 amu)

Cu-65 + (0.3083 x 64.93 amu)

Avg. mass = 63.55 amu

< > according to newton's third law of motion, forces always act in equal but opposite pairs. another way of saying this is for every action, there is an equal but opposite reaction.< >