Zirconium
Definition and meaning of Zirconium in chemistry.
![Zirconium element card: symbol Zr, atomic number 40, atomic mass 91.224, electron configuration [Kr] 4d² 5s², oxidation states +4, Transition metal, group 4, period 5, solid at room temperature.](/assets/images/terms/zirconium-chemical-element.webp)
Zirconium is a strong, gray-white transition metal that closely resembles hafnium and titanium. It has the chemical symbol Zr and the atomic number 40 on the periodic table. This tough element strongly resists corrosion from acids, alkalis, and salty sea water.
In more detail
Zirconium sits in group 4 and period 5 of the periodic table. It forms stable chemical compounds and usually has a +4 oxidation state. You will never find pure zirconium metal occurring naturally on Earth.
Instead, companies extract it mainly from a common mineral called zircon. The chemical formula for this mineral is ZrSiO4. Scientists also find this unique element in meteorites, the sun, and S-type stars.
S-type stars are a specific class of giant stars found deep in space. Zirconium handles extreme heat and harsh chemicals without breaking down. This makes it highly valuable for tough industrial settings where other metals fail.
Zirconium alloys easily let thermal neutrons pass straight through their solid structure. Thermal neutrons are slow-moving atomic particles needed to keep nuclear reactions going. This rare physical trait creates a massive global demand for zirconium metal.
Zirconium reacts quickly with oxygen, nitrogen, and carbon at very high temperatures. This fast reaction forms a hard outer layer of oxide or nitride on the metal. This tough chemical skin protects the solid metal underneath from any further damage.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Zr |
| Atomic number | 40 |
| Atomic mass | 91.224 u |
| Category | Transition-Metal |
| State at room temperature | Solid |
| Melting point | 1855 °C |
| Year discovered | 1789 |
Engineers widely use zirconium alloys to build the outer tubes for nuclear reactor fuels. These metal tubes are known as cladding in the nuclear power industry. The cladding holds the radioactive fuel safely inside the hot reactor core. Zirconium works perfectly here because it absorbs almost no thermal neutrons. This allows the important nuclear chain reaction to continue without any interruption. The metal also resists rusting or weakening in extremely hot, pressurized water. Nuclear power plants use this boiling water to generate electricity for cities.
Frequently asked questions
Is zirconium toxic?
Zirconium and its salts generally have very low toxicity. However, fine zirconium dust can cause severe fires and explosions in the air.
What is cubic zirconia?
Cubic zirconia is a human-made crystal form of zirconium dioxide (ZrO2). Jewelers widely use it as a cheap and durable fake diamond.
Related terms
Sources & references
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