The average atomic mass of lithium is 6.94 amu.
Understanding Atomic Mass
Atomic mass is a fundamental concept in chemistry, representing the mass of an atom. For elements like lithium, which exist as a mixture of isotopes, the average atomic mass is a weighted average that reflects the mass and abundance of each isotope.
What is an Isotope?
Isotopes are variants of a particular chemical element that share the same number of protons but differ in the number of neutrons. This difference in neutron count results in different atomic masses for each isotope.
Lithium Isotopes
Lithium has two stable isotopes:
- Lithium-6 (6Li)
- Lithium-7 (7Li)
Calculating Average Atomic Mass
The average atomic mass is calculated by taking into account the mass of each isotope and its natural abundance. The formula is as follows:
Average Atomic Mass = (Mass of Isotope 1 × Abundance of Isotope 1) + (Mass of Isotope 2 × Abundance of Isotope 2) + ...
Lithium's Average Atomic Mass
The average atomic mass of lithium is approximately 6.94 amu. This value indicates that 7Li is the more abundant isotope, as the average atomic mass is closer to 7 than to 6. In fact, 7Li makes up about 92.5% of naturally occurring lithium, while 6Li accounts for about 7.5%.
Practical Implications
Understanding the average atomic mass of lithium has several practical implications:
- Nuclear Applications: 6Li is used in the production of tritium, a key component in nuclear weapons and fusion reactors.
- Batteries: Lithium's light weight and electrochemical properties make it ideal for use in batteries, particularly lithium-ion batteries.
- Medicine: Lithium compounds are used in the treatment of bipolar disorder.
Summary Table
| Property | Description |
|---|---|
| Average Atomic Mass | 6.94 amu |
| Isotopes | 6Li (7.5% abundance), 7Li (92.5% abundance) |
| Most Abundant Isotope | 7Li |
