Lithium (Li)
“The featherweight of metals — light enough to float on water while it fizzes — and the beating heart of every smartphone battery.”
How its electrons are arranged
Computed from the aufbau principle, with known real-world exceptions applied automatically.
Characteristics
- The lightest metal and least dense solid element of all — about half the density of water — so a lump of lithium floats on water as it slowly fizzes away, releasing hydrogen.
- The gentlest of the alkali metals: it reacts with water far more calmly than sodium or potassium, because its small, tightly bound atom gives up its lone valence electron less willingly.
- The only alkali metal that attacks nitrogen directly at room temperature, growing a black coat of lithium nitride (Li₃N) — one good reason it must be stored under oil.
- Configuration 1s² 2s¹ — a helium-like filled inner shell plus one outsider electron, which it lets go so easily that the tiny Li⁺ ion becomes the courier of rechargeable batteries.
A soft, silvery-white metal light enough (density 0.534 g/cm³) to float not just on water but even on oil — while steadily reacting with the water. It is soft enough to slice with a knife, though in air its shine quickly dulls to grey as it reacts with nitrogen and oxygen.
Where you meet it
✦ Uses
- Lithium-ion rechargeable batteries — powering smartphones, laptops, electric cars and grid-storage stations; lithium’s low weight and high electrode potential make it almost unbeatable.
- Psychiatric medicine: lithium carbonate tablets are a long-established prescription that smooths out the extreme highs and lows of bipolar disorder.
- Aircraft and spacecraft alloys: blending just 1–2% lithium into aluminium makes structural parts meaningfully lighter yet stiffer.
- Lithium grease for vehicle wheel bearings and the lithium bromide coolant inside air-conditioning systems, both everyday industrial chemistry.
◍ Everyday examples
- The phone in a student’s pocket: its lithium-ion battery charges and discharges by shuttling Li⁺ ions back and forth between two electrodes.
- A pea-sized piece of lithium dropped in a beaker floats and fizzes gently — the famous first demonstration of an alkali metal that opens many chemistry classes.
- Ceramic cookware and heat-proof oven dishes often contain lithium compounds that let them survive sudden swings of temperature.
History & name
In 1817 the young Swedish chemist Johan August Arfwedson was analysing the mineral petalite from Utö island when his arithmetic refused to balance: the components he could identify fell short of the mineral’s total mass by a few per cent. The missing share, he concluded, was a new alkali metal, the lightest yet known. His mentor Jöns Jacob Berzelius named it lithium, from the Greek lithos, “stone”, because — unlike sodium and potassium, extracted from plant and animal material — this newcomer had been found in a mineral. The pure metal itself only appeared in 1818–1821, when William Thomas Brande in London, applying Davy’s brand-new technique of electrolysis, finally isolated it.