Final answer:
The average mass of one lithium atom is approximately 6.941 amu, and when converted into grams, it is 1.152 × 10^-23 grams. This calculation uses the atomic masses and abundances of lithium's isotopes from naturally occurring sources.
Step-by-step explanation:
The average mass of one lithium atom can be calculated using the isotope abundances and their respective atomic masses. According to given data, the isotopic composition of lithium from naturally occurring minerals shows that lithium exists primarily as two isotopes: Lithium-6 (6Li) with an atomic mass of 6.01512 atomic mass units (amu) and Lithium-7 (7Li) with an atomic mass of 7.01600 amu. The abundance of these isotopes in natural lithium is 7.5% for 6Li and 92.5% for 7Li. Using this information, the average atomic mass can be calculated as follows:
- (6.01512 amu × 0.075) + (7.01600 amu × 0.925) = 0.45114 amu + 6.4898 amu = 6.94094 amu
Therefore, the average mass of one lithium atom from naturally occurring sources is approximately 6.941 amu. Given that 1 amu is equal to 1.66053907 × 10-24 grams, we can convert this mass into grams:
6.941 amu × (1.66053907 × 10-24 grams/amu) = 1.15217177 × 10-23 grams.
The mass of a single lithium atom is thus 1.152 × 10-23 grams.