Zinc (Zn)

Zinc (symbol Zn) is the chemical element with atomic number 30: a transition metal, solid at 0 °C, with an atomic mass of 65.38 u. Discovered in 1746 (Andreas Sigismund Marggraf).

Zinc is a bluish metal used mainly to protect steel from rust: it corrodes in its place, sacrificing itself. Alloyed with copper, it forms brass, golden and easy to work. Essential to life, it helps hundreds of enzymes function. In Paris, it covers a large share of the Haussmann-era rooftops.

Key facts

Atomic number: 30
Symbol: Zn
French name: Zinc
Atomic mass: 65.38 u
Molar mass: 65.38 g/mol
Family: Transition metals
Position: period 4, group 12, d-block
State at 0 °C: Solid
Melting point: 419.5 °C
Boiling point: 906.9 °C
Density: 7.14 g/cm³
Electronegativity (Pauling): 1.65
First ionization energy: 906 kJ/mol
Atomic radius: 135 pm
Electron configuration: [Ar] 3d¹⁰ 4s²
Abundance in Earth's crust: 70 ppm (24th most abundant element)
Indicative price: 3 $/kg (order of magnitude)
Radioactive: no
Discovery: 1746, Andreas Sigismund Marggraf

Origin of the name

From the German Zinke, prong, for the shape of its crystals.

What does zinc look like?

A bluish-gray metal, brittle when cold but malleable at around 100 to 150 °C. In air, it develops a protective matte gray patina.

Where is zinc found?

About 70 ppm of Earth's crust, mainly as sulfide (sphalerite), often alongside lead. The human body contains about 2 to 3 g, mainly in muscles and bones.

Natural sources

Sphalerite (zinc blende)
Smithsonite
Hemimorphite
Zincite

How is zinc produced?

The ore is roasted, then dissolved in sulfuric acid, and the zinc is recovered by electrolysis. Mine production is around 12 million tonnes a year, making it the fourth most-produced metal after iron, aluminium and copper.

Top producers

China
Peru
Australia
India

What is zinc used for?

Galvanizing steel (about half of use).
Brass (copper-zinc) for faucets, locks and instruments.
Zamak die-cast parts (handles, toys).
Roofing and gutters.
Zinc oxide for rubber, sunscreens and ointments.
Alkaline and zinc-carbon batteries.

In everyday life

Zinc roofs and gutters
Galvanized highway guardrails
Diaper rash cream (zinc oxide)
Alkaline batteries
Zamak door handles

Role in living things

Essential: it is required by more than 300 enzymes and by many gene-controlling proteins (“zinc fingers”). It plays a role in immunity, wound healing, taste and smell. Oysters, red meat and seeds are good sources.

Hazards of zinc

Of low toxicity, but inhaling zinc oxide fumes when welding galvanized steel causes “metal fume fever,” a passing flu-like illness. Taking too much zinc in supplements over a long period can lead to copper deficiency.

Cosmic origin

Supernovae: Forged in the cores of massive stars, then scattered when they explode.

History of zinc

Brass has been known since antiquity, made without anyone knowing how to isolate zinc. In India, at Zawar (Rajasthan), metallic zinc was being distilled from around the 12th century. In Europe, Andreas Marggraf described and methodically isolated it in 1746; the name comes from the German Zinke, “prong,” perhaps for the shape of its crystals.

Did you know?

The zinc roofs of Paris, which became widespread under Haussmann in the 19th century, are candidates for UNESCO World Heritage listing.
Since 1982, the US penny has been 97.5% zinc, simply plated with copper.
The word “galvanize” honors Luigi Galvani, even though the hot-dip zinc-coating process was patented by Frenchman Stanislas Sorel in 1837.

Isotopes of zinc

Five stable isotopes, with zinc-64 making up nearly half. Zinc depleted in zinc-64 is added to the water of some reactors to curb corrosion and radioactivity.

zinc-64: 49.17% of natural zinc, stable. Removed from the zinc injected into reactors, since it would turn into radioactive zinc-65.
zinc-65: radioactive, half-life 244 days. Tracer for studying zinc absorption and alloy wear.
zinc-66: 27.73% of natural zinc, stable
zinc-67: 4.04% of natural zinc, stable
zinc-68: 18.45% of natural zinc, stable. Target for producing medical gallium-68 and copper-67.
zinc-70: 0.61% of natural zinc, stable

Related elements

Same family (transition metals): Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Yttrium (Y), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technetium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Hafnium (Hf), Tantalum (Ta), Tungsten (W), Rhenium (Re), Osmium (Os), Iridium (Ir), Platinum (Pt), Gold (Au), Mercury (Hg), Rutherfordium (Rf), Dubnium (Db), Seaborgium (Sg), Bohrium (Bh), Hassium (Hs).

Same column (group 12): Cadmium (Cd), Mercury (Hg), Copernicium (Cn).