Lithium
Atomic Data
| Atomic Number | 3 |
| Symbol | Li |
| Atomic Weight | 6.94 u |
| Density (STP) | 0.534 g/cm³ |
| Melting Point | 180.5 °C (453.65 K) |
| Boiling Point | 1329.85 °C (1603 K) |
| Electronegativity | 0.98 (Pauling) |
| Electron Config. | 1s2 2s1 |
| Oxidation States | +1 |
| Phase at STP | Solid |
| Category | Alkali Metal |
| Period / Group | 2 / 1 |
| CAS Number | 7439-93-2 |
Electron Configuration
[He] 2s1
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 1 | 3 |
| Total | 3 | 3 | ||
Abundance & Occurrence
Lithium is present in Earth's crust at approximately 20 ppm by mass and at approximately 6 ppm by mass throughout the universe.
Earth's Crust (ppm by mass)
Universe (ppm by mass)
Discovery & History
Read more about the discovery of the periodic table of elements →
Safety & Handling
- Water reactivity: Lithium metal reacts readily with water and moist air, liberating flammable hydrogen gas and producing lithium hydroxide, a strongly alkaline corrosive; the reaction intensifies with temperature.
- Fire hazard: Lithium fires cannot be extinguished with water or CO2; dry sand, lithium chloride powder, or Class D extinguishers are required. Burning lithium emits a brilliant white flame.
- Skin and eye contact: Contact with lithium metal or concentrated lithium compounds causes chemical burns; lithium hydroxide formed on moist skin is particularly aggressive and requires immediate, prolonged water flushing.
- Lithium-ion battery hazards: Damaged or overcharged lithium batteries can enter thermal runaway, releasing flammable gases and toxic fumes; damaged cells must never be punctured or charged.
- Storage: Store under mineral oil or inert gas (argon) in a cool, dry location; never allow contact with water, oxidisers, or chlorinated solvents.
Lithium in the Real World
Real-World Uses
- Lithium-ion batteries — Lithium is the active anode material in rechargeable lithium-ion cells that power smartphones, laptops, electric vehicles, and grid-scale energy storage systems.
- Mental health medication — Lithium carbonate and lithium citrate are first-line mood-stabilisers for bipolar disorder, having been in clinical use since the 1950s.
- Heat-resistant glass and ceramics — Lithium oxide is added to glass-ceramic cookware (such as Pyroceram) and telescope mirror blanks to minimise thermal expansion and prevent cracking under temperature changes.
- Lubricating greases — Lithium-based soaps thicken mineral or synthetic base oils into greases used in automotive wheel bearings, electric motors, and industrial machinery, valued for their wide temperature range and water resistance.
- Nuclear fusion fuel — Lithium-6 is irradiated in reactors to breed tritium, one of the two hydrogen isotopes needed for deuterium-tritium fusion reactions in both current research reactors and proposed power plants.
- Air treatment — Lithium hydroxide canisters absorb carbon dioxide exhaled by astronauts and submariners, keeping CO₂ levels safe in closed environments such as the Apollo spacecraft and nuclear submarines.
Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.
Frequently Asked Questions
What is lithium used for?
Lithium is best known as the key element in lithium-ion batteries that power smartphones, laptops, and electric vehicles. It is also used in psychiatric medicine (lithium carbonate as a mood stabiliser for bipolar disorder), in heat-resistant glass and ceramics, as a lubricating grease additive, and in air treatment systems aboard submarines and spacecraft where lithium hydroxide absorbs exhaled carbon dioxide.
Is lithium a metal?
Yes, lithium is a metal — in fact it is the lightest metal on the periodic table, with a density of only 0.534 g/cm³, which means it floats on water. It belongs to Group 1 (the alkali metals) and has a silvery-white appearance when freshly cut, though it tarnishes quickly in air.
Why is lithium used in batteries?
Lithium is ideal for batteries because it has the highest electrochemical potential (most negative standard reduction potential) of any element, meaning it releases the most energy per unit mass when oxidised. Its small atomic radius allows lithium ions to move rapidly through electrolytes and electrode materials, enabling fast charging and high power density. These properties combine to give lithium-ion batteries their unmatched energy density.
Is lithium dangerous?
Lithium metal reacts vigorously with water, producing hydrogen gas and lithium hydroxide and generating enough heat to ignite the hydrogen. It also ignites in air when finely divided. The pharmaceutical doses of lithium salts used to treat bipolar disorder have a narrow therapeutic window; toxicity (lithium poisoning) can occur at blood levels only slightly above the therapeutic range, causing tremor, confusion, and in severe cases seizures and kidney damage.