Final answer:
The average atomic mass of a lithium atom can be calculated by considering the mass and abundance of its isotopes. In this case, the two isotopes have masses of 6.0151 amu and 7.0160 amu, with abundances of 7.59% and 92.41% respectively. By multiplying the mass of each isotope by its abundance and summing the results, we find the average atomic mass to be 6.9323 amu.
Step-by-step explanation:
The proper calculation of the average atomic mass of a lithium atom involves considering the precise mass and natural abundance of its isotopes. In this case, we have two isotopes of lithium: 6.0151 amu with a natural abundance of 7.59% and 7.0160 amu with a natural abundance of 92.41%. To calculate the average atomic mass, we multiply each isotope's mass by its respective abundance, then sum the results:
Average Atomic Mass = (6.0151 amu * 0.0759) + (7.0160 amu * 0.9241) = 0.4564 amu + 6.4759 amu = 6.9323 amu.