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Atomic symbol: Zr |
Atomic number: 40 |
Atomic weight: 91.22 |
Atomic volume: 14.1 cm3/mol |
Density: 6.4 g/cm3 |
Period Number: 5 |
Group number: 4 |
Group name: Trans. Met. |
Element classification: Metal |
Phase at room temperature: Solid |
Melting Point: 2125.2 K |
Boiling point: 4473 K |
Heat of fusion: 16.90 kJ/mol |
Heat of vaporization: 58.20 kJ/mol |
Ionization Energy: 6.634 eV |
1st ionization energy: 660 kJ/mole |
2nd ionization energy: 1266.8 kJ/mole |
3rd ionization energy: 2218.2 kJ/mole |
Electronegativity: 1.33 |
Electron affinity: 41.1 kJ/mole |
Specific heat: 0.27 J/gK |
Heat atomization: 609 kJ/mole atoms |
Shells: 2,8,18,10,2 |
Electron Shell Configuration: [Kr] 4d2 5s2 |
Minimum oxidation number: 0 |
Maximum oxidation number: 4 |
Minimum common oxidation number: 0 |
Maximum common oxidation no: 4 |
Appearance & Characteristics |
Structure:: hcp: hexagonal close pkd |
Color: grayish-white |
Hardness: mohs |
Toxicity: ? |
Characteristics: hard, relatively inert |
Uses: deodorants, fuel rod clad |
Reaction with air: mild, w/ht =>Zr2O3 |
Reaction with 6M HCl: none |
Reaction with 15M HNO3: passivated |
Reaction with 6M NaOH: none |
Number of isotopes: 5 |
Oxide(s): ZrO2 |
Hydride(s): ZrH2 |
Chloride(s): ZrCl3 ZrCl4 |
Atomic Radius: 160 pm |
Ionic radius (1- ion): pm |
Ionic radius (1+ ion): pm |
Ionic radius (2- ion): pm |
Ionic radius (2+ ion): pm |
Ionic radius (3+ ion): pm |
Thermal conductivity: 22.7 J/m-sec-deg |
Electrical conductivity: 25 1/mohm-cm |
Polarizability: 17.9 A^3 |
Source: Zircon (silicate) |
Relative abundance solar system: 1.057 log |
Abundance earth's crust: 2.24 log |
Estimated crustal abundance: 1.65×102 milligrams per kilogram |
Estimated oceanic abundance: 3×10-5 milligrams per liter |
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(Persian zargun: gold like) Zircon, the primary gemstone of zirconium, is also known as jargon, hyacinth, jacinth, or ligure. This mineral, or its variations, is mentioned in biblical writings. The mineral was not known to contain a new element until Klaproth, in 1789, analyzed a jargon from from Ceylon and found a new earth, which Werner named zircon (silex circonius), and Klaproth called Zirkonertz (zirconia). The impure metal was first isolated by Berzelius in 1824 by heating a mixture of potassium and potassium zirconium fluoride in a small decomposition process they developed. |
Zirconium is found in abundance in S-type stars, and has been identified in the sun and meteorites. Analysis of lunar rock samples obtained during the various Apollo missions to the moon show a surprisingly high zirconium oxide content, compared with terrestrial rocks. |
Reactor-grade zirconium is essentially free of hafnium. Zircaloy(R) is an important alloy developed specifically for nuclear applications. Zirconium is exceptionally resistant to corrosion by many common acids and alkalis, by sea water, and by other agents. Alloyed with zinc, zirconium becomes magnetic at temperatures below 350K. |
It is used extensively by the chemical industry where corrosive agents are employed. Zirconium is used as a getter in vacuum tubes, as an alloying agent in steel, in surgical appliances, photoflash bulbs, explosive primers, rayon spinnerets, lamp filaments, etc. It is used in poison ivy lotions in the form of the carbonate as it combines with urushiol. With niobium, zirconium is superconductive at low temperatures and is used to make superconductive magnets, which offer hope of direct large-scale generation of electric power. Zirconium oxide (zircon) has a high index of refraction and is used as a gem material. The impure oxide, zirconia, is used for laboratory crucibles that will withstand heat shock, for linings of metallurgical furnaces, and by the glass and ceramic industries as a refractory material. Its use as a refractory material accounts for a large share of all zirconium consumed. |
Naturally occurring zirconium contains five isotopes. Fifteen other isotopes are known to exist. Zircon, ZrSiO4, the principal ore, is pure ZrO2 in crystalline form having a hafnium content of about 1%. Zirconium also occurs in some 30 other recognized mineral species. Zirconium is produced commercially by reduction of chloride with magnesium (the Kroll Process), and by other methods. It is a grayish-white lustrous metal. When finely divided, the metal may ignite spontaneously in air, especially at elevated temperatures. The solid metal is much more difficult to ignite. The inherent toxicity of zirconium compounds is low. Hafnium is invariably found in zirconium ores, and the separation is difficult.
Commercial-grade zirconium contains from 1 to 3% hafnium. Zirconium has a low absorption cross section for neutrons, and is therefore used for nuclear energy applications, such as for cladding fuel elements. Commercial nuclear power generation now takes more than 90% of zirconium metal production. Reactors of the commercial size, now being made, may use as much as a half-million linear feet of zirconium alloy tubing.
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