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Oxidation & Electrons | Appearance & Characteristics Reactions | Compounds | Radius | Conductivity Abundance & Isotopes 
Zirconium crystal bar. (Photo: Alchemist-hp ) |
General:
| Name: Zirconium | Symbol: Zr |
| Type: Transition Metal | Atomic weight: 91.22 |
| Density @ 293 K: 6.52 g/cm3 | Atomic volume: 14 cm3/mol |
| Discovered: Zirconium was first recognized as a new element by Martin Heinrich Klaproth in 1789 in a sample of zircon (zirconium silicate). The metal was first isolated by Jons J. Berzelius in 1824. The element name comes from the Persian word 'zargon', meaning gold-like. | |
States
| State (s, l, g): solid | |
| Melting point: 2123 K (1850 oC) | Boiling point: 4673 K (4400 oC) |
Energies
| Specific heat capacity: 0.27 J g-1 K-1 | Heat of atomization: 609 kJ mol-1 |
| Heat of fusion: 16.90 kJ mol-1 | Heat of vaporization : 590.5 kJ mol-1 |
| 1st ionization energy: 640.1 kJ mol-1 | 2nd ionization energy: 1266.8 kJ mol-1 |
| 3rd ionization energy: 2218.2 kJ mol-1 | Electron affinity: 41.1 kJ mol-1 |
Oxidation & Electrons
| Shells: 2,8,18,10,2 | Electron configuration: [Kr] 4d2 5s2 |
| Minimum oxidation number: 0 | Maximum oxidation number: 4 |
| Min. common oxidation no.: 0 | Max. common oxidation no.: 4 |
| Electronegativity (Pauling Scale): 1.33 | Polarizability volume: 17.9 Å3 |
Appearance & Characteristics
| Structure: hcp: hexagonal close pkd | Color: grayish-white |
| Hardness: 5.0 mohs | |
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Harmful effects: Zirconium is considered to be non-toxic. Characteristics: Zirconium is a strong, malleable, ductile, lustrous, grayish-white metal. It is generally exceptionally resistant to corrosion. It is however rapidly attacked by hydrofluoric acid, even at low concentrations. Powdered zirconium can spontaneously ignite in air. Exposed surfaces form a protective oxide layer. Uses: Zirconium is very poor at absorbing neutrons. It is therefore useful in nuclear energy applications such as in the cladding (outer layer) of fuel rods through which it is important that neutrons can travel easily. Zirconium is used as to make surgical instruments and is used in steel alloys as a hardening agent. As a result of its exceptional corrosion resistance, zirconium is used extensively in the chemical industry in corrosive environments where zirconium its alloys can be found in pipes, fittings and heat exchangers. Zirconium is also used to make superconductive magnets. Zircon (zirconium silicate, ZrSiO4) is a natural gemstone and synthetic cubic zirconia (zirconium dioxide, ZrO2) is produced as a low-cost substitute for diamond. Zirconium based catalysts are used in amination, hydrogenation, isomerization and oxidation reactions. Lithium zirconate can be used to absorb carbon dioxide. The reaction is reversible so the carbon dioxide can be released in a location of choice and the lithium zirconate used again. This application may be useful in addressing environmental concerns about the release of carbon dioxide into the atmosphere. |
Reactions
| Reaction with air: mild, w/ht ⇒ Zr2O3 | Reaction with 6 M HCl: none |
| Reaction with 15 M HNO3: passivated | Reaction with 6 M NaOH: none |
Compounds
| Oxide(s): ZrO2 | Chloride(s): ZrCl3, ZrCl4 |
| Hydride(s): ZrH2 |
Radius
| Atomic radius: 160 pm | Ionic radius (1+ ion): pm |
| Ionic radius (2+ ion): pm | Ionic radius (3+ ion): 88.5 pm |
| Ionic radius (2- ion): pm | Ionic radius (1- ion): pm |
Conductivity
| Thermal conductivity: 22.7 W m-1 K-1 | Electrical conductivity: 2.3 x 10-6 S m-1 |
Abundance & Isotopes
| Abundance earth's crust: 165 parts per million by weight, 38 parts per million by moles | |
| Abundance solar system: 40 parts per billion by weight, 0.5 parts per billion by moles | |
| Cost, pure: $16 per 100g | |
| Cost, bulk: $16 per 100g | |
| Source: Zirconium does not occur free in nature. Its chief mineral is zircon (zirconium silicate, ZrSiO4). It is produced commercially by reduction of the chloride with magnesium in the Kroll process. | |
| Isotopes: Zirconium has 25 isotopes whose half-lives are known, with mass numbers 81 to 105. Of these, four are stable: 90Zr, 91Zr, 92Zr and 94Zr. The most naturally abundant is 90Zr at 51.5%. | |
