1. Average Atomic Mass Practice
Silicon has 3 isotopes with the following % abundances.
Si-28, 92.23%
Si-29, 4.67%
Si-30, 3.10%
Calculate silicon’s average atomic mass.

2. Answer
(28 x ) + (29 x ) + (30 x .031) = amu

3. % Abundance Practice Silver, Ag, exists as 2 isotopes, Ag-107
and Ag Calculate the % abundance for each isotope of silver.

4. Answer
= (x)(107) + (1-x)(109) X = Ag-107 is 56.59% abundant Ag-109 is 43.41% abundant

5. 2) Lithium exists as 2 isotopes,. Li-6 and Li-7
2) Lithium exists as 2 isotopes, Li-6 and Li-7. Calculate the % abundance for each isotope of lithium.

6. Answer
6.94 = (x)(6) + (1-x)(7) X = Li-6 is 5.90% abundant Li-7 is 94.10% abundant

7. Gallium consists of two naturally occurring isotopes with masses of 69 and 71 amu. The average atomic mass of Ga is amu. Calculate the abundance of each isotope.
69Ga = 40% 71Ga = 60%
69Ga = 69% 71Ga = 31%
69Ga = 29% 71Ga = 71%
69Ga = 31% 71Ga = 69%
69Ga = 64% 71Ga = 36% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22