Lithium
Element 3 · Alkali Metal
Lithium is the first alkali metal: a silvery solid so soft it dents under a fingernail and so light it floats on oil. Like all alkali metals it reacts eagerly, tarnishing in air and fizzing in water to release hydrogen, so samples are stored under oil. Lithium's tiny ion slips easily between layers of other materials, which is exactly why lithium-ion batteries dominate phones, laptops, and electric cars. Medicine uses lithium carbonate to stabilize mood in bipolar disorder, and industry turns lithium compounds into heat-resistant glass, lubricating greases, and strong lightweight alloys.
Key facts
| Atomic number | 3 |
|---|---|
| Atomic weight | 6.94 |
| Category | Alkali Metal |
| Group / Period | 1 / 2 |
| Block | s |
| Electron configuration | 1s2 2s1 |
| Common oxidation states | +1 |
| State at STP | Solid |
| Electronegativity | 0.98 |
| Atomic radius | 167 pm |
| Density | 0.534 g/cm³ |
| Melting point | 180.54 °C |
| Boiling point | 1342 °C |
Occurrence
Lithium concentrates in salty underground brines beneath salt flats and in the mineral spodumene. The largest reserves sit in South America, Australia, and China. Seawater holds traces, but at concentrations far too low to mine economically.
Applications
Lithium-ion rechargeable batteries
Mood-stabilizing medication
High-temperature lubricating greases
Lightweight aluminium alloys for aircraft
Specialty glass and ceramics
Common compounds
- Lithium carbonate (Li2CO3)
- Lithium hydroxide (LiOH)
- Lithium chloride (LiCl)
- Spodumene (LiAlSi2O6)
Lithium is the least dense metal on Earth. It would float on water — if it did not burst into fizzing flame the moment it touched it.
Data source: IUPAC standard atomic weights 2021