Zirconium
Definition and meaning of Zirconium in chemistry.
Zirconium is a lustrous, gray-white, strong transition metal that closely resembles hafnium and, to a lesser extent, titanium. It has the chemical symbol Zr and an atomic number of 40. This element is highly resistant to corrosion by alkalis, acids, salt water, and other harsh agents.
In more detail
Located in group 4 and period 5 of the periodic table, zirconium is a transition metal that forms stable compounds with various oxidation states, most commonly +4. In nature, it never occurs as a native metal but is obtained mainly from the mineral zircon (ZrSiO4), which is found in abundance in S-type stars, the sun, and meteorites. It exhibits outstanding resistance to heat and corrosion, making it extremely valuable in harsh chemical environments where other metals would rapidly degrade. Zirconium alloys are notably transparent to thermal neutrons, a rare and essential physical property for nuclear power applications that dictates its global demand. The metal is highly reactive with oxygen, nitrogen, and carbon at elevated temperatures, forming a protective oxide or nitride layer that effectively prevents further chemical degradation of the bulk material.
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 |
| Boiling point | 4377 °C |
| Year discovered | 1789 |
Zirconium alloys are extensively used as cladding for nuclear reactor fuels because of their low absorption cross-section for thermal neutrons and excellent corrosion resistance in high-temperature water.
Frequently asked questions
Is zirconium toxic?
Zirconium and its salts generally have low systemic toxicity, though fine zirconium dust can be a severe fire and explosion hazard in the air.
What is cubic zirconia?
Cubic zirconia is the synthesized cubic crystalline form of zirconium dioxide (ZrO2), widely created for use as a durable and inexpensive diamond simulant in jewelry.