Lithium
Lithium is the lightest metal on the periodic table, soft enough to cut with a knife and light enough to float on water — though it reacts with water rather than just sitting on it. As the first alkali metal, it's highly reactive and never found in nature as a free element, but in compound form it has become essential to modern rechargeable batteries.
- Group · Period
- 1 · 2
- At room temp
- solid
- Melts at
- 453.65 K
- Density
- 0.534 g/cm³
- Discovered
- 1817
Uses
Lithium’s dominant modern use is in rechargeable batteries — lithium-ion cells store energy at a high density relative to their weight, which is why they power everything from smartphones and laptops to electric vehicles and grid-scale energy storage. That single application has made lithium one of the most strategically important elements of the past few decades.
Outside batteries, lithium carbonate has long been used as a mood-stabilizing medication for bipolar disorder, one of the oldest and still widely prescribed treatments of its kind. Lithium compounds also show up in specialty glass and ceramics, where they lower melting points and improve thermal shock resistance, and in greases formulated to perform well across a wide temperature range.
History
Lithium was discovered in 1817 by Swedish chemist Johan August Arfwedson, who was analyzing the mineral petalite in the laboratory of the famous chemist Jöns Jacob Berzelius and found a new alkali element within it. Unlike sodium and potassium, which were already known from plant ash, this one turned up in a mineral, so Arfwedson and Berzelius named it lithium, from the Greek “lithos,” meaning stone. It took several more years before other chemists managed to isolate lithium in its pure metallic form.
Fun facts
- Lithium is the lightest of all metals, roughly half the density of water, so a chunk of it would float — right up until it started reacting.
- It's the key ingredient in lithium-ion batteries, the rechargeable technology behind most phones, laptops, and electric vehicles.
- Lithium compounds have been used since the mid-20th century as mood-stabilizing medication for bipolar disorder, one of the few metals with a major role in psychiatric medicine.
Frequently asked questions
Why does lithium float on water if it's a metal?
Metals are usually thought of as dense, but lithium is unusually light — about half the density of water. It does float briefly, but it also reacts with water, fizzing as it produces hydrogen gas and a lithium hydroxide solution, so it doesn't stay a solid floating chunk for long.
Is lithium metal as dangerous to handle as sodium or potassium?
It's reactive with air and water and needs to be stored away from moisture, usually under oil, but it reacts noticeably less violently than sodium or potassium. All three are alkali metals with a similar chemistry, but reactivity increases as you go down the group, and lithium sits at the mild end.
Where does the lithium in batteries actually come from?
Mainly two sources: mineral ore deposits containing lithium-bearing rock like spodumene, which is mined and processed directly, and brine deposits in salt flats, where lithium-rich water is pumped out and concentrated through evaporation before being refined into battery-grade compounds.
Compounds
5 notable compounds containing Li
- Li2CO3salt
Lithium carbonate
A white ionic salt that is one of the few practical sources of soluble lithium ions, produced from lithium-bearing brines and minerals.
Used for: Mood-stabilizing medication for bipolar disorder
- LiClsalt
Lithium chloride
A highly hygroscopic ionic salt that pulls moisture from the air so effectively it is used as a drying agent, releasing noticeable heat as it dissolves.
Used for: Desiccant and dehumidifier, brazing flux for aluminum
- LiFsalt
Lithium fluoride
An ionic salt of small, tightly bound ions that gives it an unusually wide window of optical transparency stretching into the ultraviolet.
Used for: UV and infrared optical windows and lenses, reactor coolant salts
- LiOHbase
Lithium hydroxide
A strong alkaline compound that absorbs carbon dioxide efficiently for its weight, and a key precursor in manufacturing lithium-ion battery cathodes.
Used for: CO2 scrubbing in submarines and spacecraft, battery material production
- LiNbO3industrial
Lithium niobate
A synthetic crystal with strong piezoelectric and nonlinear-optical properties, grown in large single crystals for use throughout the electronics and photonics industries.
Used for: Surface acoustic wave filters in phones and optical modulators in telecom equipment
Isotopes
9 known isotopes
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| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Li-6 stable | 4.85% | Stable | — | 14,086.88 keV | 5,332.33 keV | — |
| Li-7 stable | 95.15% | Stable | — | 14,907.1 keV | 5,606.44 keV | — |
Show all 9 isotopes
| Li-4 | — | — | Proton emission (100%) | 25,323.19 keV | 1,153.76 keV | — |
| Li-5 | — | 1.23 MeV | Proton emission | 11,678.89 keV | 5,266.13 keV | 1.23 × 106 eV |
| Li-8 | — | 839.9 ms | Beta-minus, alpha emission (100%), Beta-minus decay (100%) | 20,945.81 keV | 5,159.71 keV | 5.43 × 10-16 eV |
| Li-9 | — | 178.3 ms | Beta-minus decay (100%), Beta-minus, neutron emission (50.8%) | 24,954.91 keV | 5,037.77 keV | 2.56 × 10-15 eV |
| Li-10 | — | — | Neutron emission (100%) | 33,052.63 keV | 4,531.35 keV | — |
| Li-11 | — | 8.75 ms | Beta-minus decay (100%), Beta-minus, neutron emission | 40,728.26 keV | 4,155.38 keV | 5.21 × 10-14 eV |
| Li-12 | — | — | Neutron emission (100%) | 49,009.58 keV | 3,791.6 keV | — |