The atomic mass of germanium is 72.61 amu. Is it likely that any individual germanium atoms have a mass of 72.61 amu?
Solution 120P
Ge have five naturally occurring isotopes from 70Ge, 72Ge, 73Ge, 74Ge, and 76Ge. The atomic mass of germanium will the average atomic mass which is between the masses of the five isotopes.
70Ge = 20.52
72Ge = 27.45%
73Ge = 7.76%
74Ge = 36.52%
76Ge= 7.75%
Therefore the standard atomic mass of germanium is calculated by using the standard formula
= 0.2052 x 69.92 + 71.9 x 0.2745 + 72.9 x 0.0776+ 73.9x 0.3652+ 0.0775 x 75.9
= 14.34 + 19.74 + 5.65+ 26.988+ 5.88
= 72.63 amu.
Therefore, individual germanium atom has average atomic mass is 76.63 amu.