Elements
The chemical elements, and what each one is actually used for.
Actinium
Ac
The element that named the actinides, now valued for a decay that destroys cells at very short range.
Aluminium
Al
The most abundant metal in the Earth's crust, and until the 1880s more valuable than gold because nobody could extract it cheaply.
Americium
Am
A synthetic element that exists in almost every home, in a quantity smaller than a grain of salt.
Arsenic
As
A semi-metal known chiefly as a poison, and a serious contaminant of groundwater for millions of people.
Barium
Ba
A metal whose compounds are either lethal or routinely swallowed, depending entirely on solubility.
Beryllium
Be
A metal stiffer than steel at a quarter the density, and toxic enough that machining it requires containment.
Bismuth
Bi
The heaviest element that is, for practical purposes, stable — and the least toxic heavy metal.
Bromine
Br
The only non-metallic element that is liquid at room temperature, and an industrial workhorse whose main use has been regulated away twice.
Californium
Cf
A synthetic element that emits neutrons steadily enough to start reactors and find oil.
Carbon
C
The element whose two common crystal forms — diamond and graphite — differ more from each other than almost any other pair of substances.
Chlorine
Cl
A green, choking gas that made drinking water safe and was the first chemical weapon used at scale.
Chromium
Cr
The element that makes stainless steel stainless, by growing an oxide layer thin enough to be invisible.
Cobalt
Co
A blue pigment for three thousand years, a battery cathode today, and a supply chain concentrated in one country.
Copper
Cu
A soft, ductile metal with exceptional electrical conductivity, and one of the first metals humans worked.
Dysprosium
Dy
The element that keeps electric vehicle motors working when they get hot, and a persistent supply worry.
Erbium
Er
The element that makes long-distance optical fibre work, by amplifying light without turning it back into electricity.
Europium
Eu
The rare earth that put red on television screens and now helps prove banknotes are genuine.
Gadolinium
Gd
A rare earth that absorbs neutrons better than almost anything and makes MRI scans readable.
Hafnium
Hf
Zirconium's near-inseparable twin, distinguished by doing the exact opposite with neutrons.
Helium
He
An inert gas that cannot be manufactured, is escaping the planet continuously, and is being spent on party balloons.
Holmium
Ho
The most magnetic of the elements, and the source of a laser wavelength that water absorbs almost completely.
Hydrogen
H
The lightest and most abundant element in the universe, and the one most often proposed as a replacement for the fuels we currently burn.
Iodine
I
An element that is essential to human development in microgram quantities and whose deficiency was once a widespread cause of preventable harm.
Iridium
Ir
The most corrosion-resistant metal known, and the fingerprint of the asteroid that ended the Cretaceous.
Krypton
Kr
A noble gas used where argon is not quite inert or not quite dense enough, and in the lamps that once lit stadiums.
Lanthanum
La
The first of the lanthanides, and the element that made nickel-metal-hydride batteries and modern oil refining work.
Magnesium
Mg
The lightest structural metal in common use, and one that burns with a light bright enough to have been used for photography.
Manganese
Mn
The element that made steel workable, and the one nobody mentions when they talk about steel.
Mercury
Hg
The only metal that is liquid at room temperature, and the one whose applications have been withdrawn one by one.
Neon
Ne
A noble gas whose only significant use is the one it is named for — glowing red in a tube — plus a quieter role in the lasers that print microchips.
Niobium
Nb
A metal that superconducts usefully, and that spent a century being confused with tantalum.
Nitrogen
N
Seventy-eight percent of the air, almost entirely unreactive, and the element whose industrial fixation roughly doubled the number of people the planet can feed.
Oxygen
O
The most abundant element in the Earth's crust, and the reason most metals must be smelted rather than found.
Palladium
Pd
The catalytic metal that cleans petrol engine exhaust, absorbs hydrogen like a sponge, and briefly became more valuable than gold.
Phosphorus
P
An element with no substitute in agriculture, mined from a small number of deposits, and discovered by boiling urine.
Platinum
Pt
A metal too refractory for the Spanish to melt, discarded as an impurity in silver, and now central to catalysis.
Plutonium
Pu
A synthetic element made in reactors, present in the environment only because people put it there.
Polonium
Po
The first element the Curies found, intensely radioactive and useful mainly for the static it removes.
Potassium
K
The third of the three elements every fertiliser is measured by, mined as ancient evaporated seawater.
Praseodymium
Pr
A rare earth used to make magnets stronger, glass yellow, and welders' goggles safe to look through.
Promethium
Pm
The lanthanide with no stable isotope, which kept watch faces glowing after radium was abandoned.
Radium
Ra
The element that made radioactivity famous, and whose consequences wrote much of modern radiation law.
Radon
Rn
A radioactive gas produced by ordinary rock, and the reason geology turns up in building regulations.
Rhenium
Re
One of the rarest elements in the crust, and the reason jet engines can run as hot as they do.
Ruthenium
Ru
A platinum-group metal that hardens its relatives, catalyses ammonia synthesis, and sits on almost every hard disk platter.
Scandium
Sc
A rare earth in everything but name, whose main use is making aluminium behave like a much better alloy.
Selenium
Se
An element that conducts better in light than in darkness — the basis of the first photocopier.
Silicon
Si
The second most abundant element in the Earth's crust, and the substrate of essentially all modern electronics.
Silver
Ag
The best electrical conductor of any element, used for almost everything except conducting electricity.
Strontium
Sr
The red in fireworks, and an element whose radioactive isotope taught the world about fallout.
Sulfur
S
The yellow element of volcanoes, and the feedstock for the chemical the world produces more of than any other.
Tantalum
Ta
The capacitor metal, and the one whose supply chain forced an industry to think about where its materials come from.
Technetium
Tc
The first element made rather than found, and now the one most often injected into human beings.
Terbium
Tb
The green in a colour screen, and a metal that changes shape in a magnetic field enough to be useful.
Thallium
Tl
A metal whose main historical use was killing things, and which is now mostly encountered as a problem.
Thorium
Th
A potential nuclear fuel that is several times more abundant than uranium and has never been commercialised.
Thulium
Tm
The rarest of the stable lanthanides, whose main job is to make X-rays without a power supply.
Tin
Sn
A soft, low-melting metal whose main historical significance is that adding it to copper makes bronze.
Titanium
Ti
As strong as steel at half the weight, abundant in the crust, and expensive because it is difficult to extract rather than rare.
Tungsten
W
The highest melting point of any metal, which is why lightbulb filaments were made of it and why it is used to drill through everything else.
Uranium
U
An element used as a yellow glass colourant for a century before anyone knew it was radioactive.
Vanadium
V
The addition that made tool steel hold an edge, named after a Norse goddess for the colours of its compounds.
Xenon
Xe
The noble gas that anaesthetises without side effects, propels spacecraft, and produces light close to daylight.