Lithium (Li)

Lithium (symbol Li) is the chemical element with atomic number 3: an alkali metal, solid at 0 °C, with an atomic mass of 6.94 u. Discovered in 1817 (Johan August Arfwedson).

Lithium is a metal so light it floats on oil. Highly reactive, it never occurs in pure form in nature. Its ability to store a lot of energy in very little mass has made it the key to batteries for phones and electric cars. It is also a mainstay treatment for bipolar disorder.

Key facts

Atomic number: 3
Symbol: Li
French name: Lithium
Atomic mass: 6.94 u
Molar mass: 6.94 g/mol
Family: Alkali metals
Position: period 2, group 1, s-block
State at 0 °C: Solid
Melting point: 180.5 °C
Boiling point: 1,329.9 °C
Density: 0.53 g/cm³
Electronegativity (Pauling): 0.98
First ionization energy: 520 kJ/mol
Atomic radius: 145 pm
Electron configuration: [He] 2s¹
Abundance in Earth's crust: 20 ppm (32nd most abundant element)
Indicative price: 83 $/kg (order of magnitude)
Radioactive: no
Discovery: 1817, Johan August Arfwedson

Origin of the name

From the Greek lithos, stone.

What does lithium look like?

A silvery-white metal, soft enough to cut with a knife, that quickly tarnishes in air under a gray-to-black coating. Its density (0.53) is about half that of water.

Where is lithium found?

About 20 ppm of Earth's crust. It is found in granitic rocks (pegmatites) and above all in brines, very salty waters trapped beneath the salt flats of South America. Seawater contains about 0.18 mg per liter.

Natural sources

Spodumene
Lepidolite
Petalite
Amblygonite
Salt-flat brines

How is lithium produced?

Brines are pumped up and left to evaporate in the sun for months in vast ponds; hard-rock ores are crushed and treated chemically. The pure metal is obtained by electrolysis of molten lithium chloride. World output has topped 200,000 tonnes of contained lithium a year and is rising fast.

Top producers

Australia
Chile
China
Argentina
Zimbabwe

What is lithium used for?

Lithium-ion batteries (more than three quarters of demand).
Glass and ceramics that withstand thermal shock (glass-ceramic cooktops).
Lubricating greases for cars and industry.
Mood-stabilizing medication (lithium carbonate).
Lightweight aluminium-lithium alloys for aircraft.

In everyday life

The battery in your smartphone and laptop
Electric cars and scooters
Lithium coin cells
A glass-ceramic cooktop

Role in living things

Not essential to life, but present in trace amounts in water and food. In carefully controlled doses it stabilizes mood in people with bipolar disorder, an effect discovered by Australian psychiatrist John Cade in 1949. Several studies suggest a link between trace lithium in drinking water and lower suicide rates.

Hazards of lithium

The metal reacts with water, releasing flammable hydrogen. Damaged lithium-ion batteries can go into thermal runaway and catch fire. In medicine, the gap between an effective and a toxic dose is narrow, hence regular blood tests.

Cosmic origin

Dying stars: Made slowly in red giants (stars like the Sun at the end of their lives).
Cosmic rays: Born from the fragmentation of heavier atoms struck by high-energy particles.
Big Bang: Forged in the first three minutes of the Universe, 13.8 billion years ago.

History of lithium

In 1817, Swedish chemist Johan August Arfwedson discovered it in petalite, an ore from the island of Utö. Because it was found in a stone rather than a plant, it was named after the Greek lithos, “stone.” The metal was isolated in 1821 by William Brande, then produced in quantity by Bunsen and Matthiessen in 1855.

Did you know?

The soft drink 7 Up contained lithium citrate from its launch in 1929 until 1948.
Lithium is one of only three elements formed in significant amounts in the Big Bang.
It turns flames a vivid crimson red, which is why it is used in fireworks.

Isotopes of lithium

Two stable isotopes, lithium-6 and lithium-7. Lithium-6 is strategic because it breeds the tritium that nuclear fusion needs.

lithium-6: 7.59% of natural lithium, stable. Hit with neutrons, it yields tritium for fusion and thermonuclear weapons.
lithium-7: 92.41% of natural lithium, stable. Used to control the water chemistry in some nuclear reactors.

Common compounds

Lithium cobalt oxide (LiCoO₂) · Lithium iron phosphate (LiFePO₄)

Related elements

Same family (alkali metals): Sodium (Na), Potassium (K), Rubidium (Rb), Caesium (Cs), Francium (Fr).

Same column (group 1): Hydrogen (H), Sodium (Na), Potassium (K), Rubidium (Rb), Caesium (Cs), Francium (Fr).