Question

find the average atomic mass (atomic weight) for lithium on the periodic table. there are only two significant isotopes of lithium, li - 6 and li - 7. which is the most abundant isotope? the periodic table gives 1. this is very close to 2 so 3 is the most abundant isotope and only a small amount of 4 is found on earth. a. li - 7 b. li - 6 c. 6.941

Explanation:

Step1: Recall periodic - table value

The average atomic mass of lithium from the periodic table is 6.941.

Step2: Analyze isotopes' masses

Li - 6 has a mass of approximately 6 and Li - 7 has a mass of approximately 7. 6.941 is closer to 7.

Step3: Determine abundance

Since the average atomic mass is closer to 7, Li - 7 is the most abundant isotope and only a small amount of Li - 6 is found on earth.

Answer:

1. C. 6.941
2. A. Li - 7
3. A. Li - 7
4. B. Li - 6