|
General |
Name, Symbol, Number | Zirconium, Zr, 40 |
Chemical series | transition metals |
Group, Period, Block | 4[?], 5 , d |
Density, Hardness | 6511 kg/m3, 5 |
Appearance | Silvery white |
Atomic Properties |
Atomic weight | 91.224 amu |
Atomic radius (calc.) | 155 (206) pm |
Covalent radius | 148 pm |
van der Waals radius | no data |
Electron configuration | [Kr]4d25s2 |
e- 's per energy level | 2, 8, 18, 10, 2 |
Oxidation states (Oxide) | 4 (amphoteric) |
Crystal structure | Hexagonal |
Physical Properties |
State of matter | Solid (__) |
Melting point | 2128 K (3371 °F) |
Boiling point | 4682 K (7968 °F) |
Molar volume | 14.02 ×10-3 m3/mol |
Heat of vaporization | 58.2 kJ/mol |
Heat of fusion | 16.9 kJ/mol |
Vapor pressure | 0.00168 Pa at 2125 K |
Speed of sound | 3800 m/s at 293.15 K |
Miscellaneous |
Electronegativity | 1.33 (Pauling scale) |
Specific heat capacity | 0.27 J/(kg*K) |
Electrical conductivity | 2.36 106/m ohm |
Thermal conductivity | 22.7 W/(m*K) |
1st ionization potential | 640.1 kJ/mol |
2nd ionization potential | 1270 kJ/mol |
3rd ionization potential | 2218 kJ/mol |
4th ionization potential | 3313 kJ/mol |
5th ionization potential | 7752 kJ/mol |
6th ionization potential | 9500 kJ/mol |
Most Stable Isotopes |
|
SI units & STP are used except where noted. |
Zirconium is a
chemical element in the
periodic table that has the symbol Zr and
atomic number 40. A lustrous gray-white, strong
transition metal that resembles
titanium, zirconium is obtained chiefly from
zircon and is very corrosion resistant. Zirconium is primarily used in
nuclear reactors for a neutron absorber and to make
corrosion-resistant alloys.
It is a grayish-white
metal, lustrous and exceptionally corrosion resistant. Zirconium is lighter than
steel and its hardness is similar to
copper. When it is finely divided, the metal can spontaneously ignite in air, especially at high temperatures (it is much more difficult to ignite the solid metal). Zirconium zinc
alloy becomes
magnetic at temperatures below 35°
K. Common
oxidation states of zirconium include +2, +3 and +4.
The major end uses of
zircon (Zr
SiO4) are refractories, foundry sands (including investment casting), and
ceramic opacification. Zircon is also marketed as a natural
gemstone used in
jewelry, and its oxide is processed to produce the
diamond stimulant,
cubic zirconia. Other uses;
- Zirconium has a low absorption cross section for neutrons, which makes it ideal for nuclear energy uses, such as cladding fuel elements. More than 90% of zirconium metal production is consumed by commercial nuclear power generation. Modern commercial scale reactors can use as much as a half-million linear feet of zirconium alloy tubing.
- Extensively used by the chemical industry for piping in corrosive environments.
- Zirconium is pyrophoric (flammable) and has been used in military incendiaries.
- Its carbonate is used in poison ivy lotions.
- Impure zirconium oxide, zirconia, is used to make laboratory crucibles that can withstand heat shock, for linings of metallurgical furnaces, and by the ceramic and glass industries as a refractory material.
- Human tissues can easily tolerate this metal which makes it suitable for some artificial joints and limbs.
- Also used in heat exchangers, as a "getter" in vacuum tubes, in lamp filaments and various specialty alloys.
When alloyed with niobium, zirconium becomes superconductive at low temperatures and is used to make superconductive magnets with possible large-scale electrical power[?] uses.
Zirconium (
Arabic zarkūn from
Persian zargūn meaning "gold like") was
discovered in
1789 by
Martin Klaproth[?] and isolated in
1824 by
Jons Jakob Berzelius.
The zirconium containing mineral zircon, or its variations (jargon, hyacinth, jacinth, or ligure), were mentioned in biblical writings. The mineral was not known to contain a new element until Klaproth analyzed a jargon from from Ceylon in the Indian Ocean. He named the new element Zirkonertz (zirconia). The impure metal was isolated first by Berzelius by heating a mixture of potassium and potassium zirconium fluoride in a small decomposition process conducted in an iron tube. Pure zirconium wasn't prepared until 1914.
Zirconium is never found in nature as a free metal. The principal economic source of zirconium is the zirconium silicate mineral, zircon (ZrSiO
4) which is found in deposits located in
Australia,
Brazil,
India,
Russia, and the
United States (it is extracted as a dark sooty powder, or as a gray metallic crystalline substance). Zirconium and
hafnium are contained in zircon at a ratio of about 50 to 1 and are difficult to separate. Zircon is a coproduct or byproduct of the mining and processing of heavy-mineral sands for the
titanium minerals,
ilmenite and
rutile, or
tin minerals. Zirconium is also in 30 other recognized mineral species including
baddeleyite. This metal is commercially produced by reduction of the chloride with
magnesium in the
Kroll Process[?], and through other methods. Commercial-quality zirconium still has a content of 1 to 3% hafnium.
This element is also abundant in S-type stars, and has been detected in the sun and meteorites. Lunar rock samples brought back from several Apollo program missions to the moon have a very high zirconium oxide content relative to terrestrial rocks.
Naturally occurring zirconium is composed of four stable isotopes and one extremely long-lived
radioisotope (Zr-96). The second most stable
radioisotope is Zr-93 which has a
half life of 1.53 million years. Eighteen other radioisotopes have been characterized. Most of these have half lives that are less than a day except Zr-95 (64.02 days), Zr-88 (63.4 days), and Zr-89 (78.41 hours). The primary decay mode is
electron capture before Zr-92 and the primary mode after is
beta decay.
Compounds containing zirconium are encountered relatively rarely by most people and their inherent toxicity is low. The metal dust can ignite in air and should be regarded as a major fire and explosion hazard. Zirconium has no biological role.