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3Li6.94

Element 3, an alkali metal

Lithium

The lightest metal of all: soft enough to cut with a knife, light enough to float on oil, and the heart of the rechargeable battery in your pocket.

At a glance

Symbol
Li
Atomic number
3
Average atomic mass
6.94
Group
1
Period
2
Family
alkali metal
Electron configuration
1s² 2s¹, or [He] 2s¹
Valence electrons
1
Electronegativity
0.98
Common ions
Li⁺

On the table

Periodic table with Lithium highlighted123456789101112131415161718123456757-7189-103HHeLiBeBCNOFNeNaMgAlSiPSClArKCaScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSrYZrNbMoTcRuRhPdAgCdInSnSbTeIXeCsBaLaCePrNdPmSmEuGdTbDyHoErTmYbLuHfTaWReOsIrPtAuHgTlPbBiPoAtRnFrRaAcThPaUNpPuAmCmBkCfEsFmMdNoLrRfDbSgBhHsMtDsRgCnNhFlMcLvTsOg

Period 2, group 1. The other alkali metals are tinted, and every cell opens its own article.

Electrons and bonding

Li

One valence electron, which lithium gives up easily to form the Li⁺ ion. Like the other alkali metals, it reacts with water.

Properties

State at 25 °C
solid
What it looks like
soft, silvery-white metal that tarnishes quickly in air
Melting point
180.5 °C
Boiling point
1342 °C
Density
0.534 g/cm³
Flame test
crimson red

Where it is found

Too reactive to occur as a metal. Most comes from salty brines pumped from beneath salt flats in Chile and Argentina and evaporated in huge ponds, and from the mineral spodumene mined in Australia. Seawater holds about 0.2 parts per million.

Discovery and name

Johan August Arfwedson found it in 1817 in the mineral petalite, from the Swedish island of Utö. It was named from the Greek lithos, stone, because it turned up in a mineral rather than in plant ash like sodium and potassium. William Thomas Brande and Humphry Davy first isolated the metal by electrolysis.

What it is used for

Lithium-ion batteries for phones, laptops and electric cars now use most of it. It also goes into heat-resistant glass and ceramics, long-lasting grease, and light aluminum alloys for aircraft. Lithium carbonate has treated bipolar disorder for decades.

In compounds

Li₂CO₃lithium carbonate, a medicine and battery materialLiOHlithium hydroxide, scrubs CO₂ from spacecraft airLiCoO₂lithium cobalt oxide, a battery cathodeLiFlithium fluorideLi₃Nlithium nitrideLiAlH₄lithium aluminum hydride, a lab reducing agent

Handle with care

Reacts with water to release flammable hydrogen, and damaged lithium-ion batteries can overheat and catch fire.