Zirconium

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yttrium ? zirconium ? niobium Ti ? Zr ? Hf 40Zr Periodic table Appearance silvery white General properties Name, symbol, number zirconium, Zr, 40 Element category transition metal Group, period, block 4, 5, d Standard atomic weight 91.224?g¡mol?1 Electron configuration [Kr] 4d2 5s2 Electrons per shell 2, 8, 18, 10, 2 (Image) Physical properties Phase solid Density (near r.t.) 6.52 g¡cm?3 Liquid density at m.p. 5.8 g¡cm?3 Melting point 2128 K,?1855 Â°C,?3371 Â°F Boiling point 4682 K,?4409 Â°C,?7968 Â°F Heat of fusion 14 kJ¡mol?1 Heat of vaporization 573 kJ¡mol?1 Specific heat capacity (25 °C) 25.36 J¡mol?1¡K?1 Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K 2639 2891 3197 3575 4053 4678 Atomic properties Oxidation states 4, 3, 2, 1,[1] (amphoteric oxide) Electronegativity 1.33 (Pauling scale) Ionization energies 1st: 640.1 kJ¡mol?1 2nd: 1270 kJ¡mol?1 3rd: 2218 kJ¡mol?1 Atomic radius 160 pm Covalent radius 175Âą7 pm Miscellanea Crystal structure hexagonal close-packed Magnetic ordering paramagnetic[2] Electrical resistivity (20 Â°C) 421 n?¡m Thermal conductivity (300 K) 22.6 W¡m?1¡K?1 Thermal expansion (25 °C) 5.7 Âľm¡m?1¡K?1 Speed of sound (thin rod) (20 °C) 3800 m/s Young's modulus 68 GPa Shear modulus 33 GPa Poisson ratio 0.34 Mohs hardness 5.0 Vickers hardness 903 MPa Brinell hardness 650 MPa CAS registry number 7440-67-7 Most stable isotopes Main article: Isotopes of zirconium iso NA half-life DM DE (MeV) DP 88Zr syn 83.4 d ? - 88Y ? 0.392D - 89Zr syn 78.4 h ? - 89Y ?+ 0.902 89Y ? 0.909D - 90Zr 51.45% 90Zr is stable with 50 neutrons 91Zr 11.22% 91Zr is stable with 51 neutrons 92Zr 17.15% 92Zr is stable with 52 neutrons 93Zr 17.38% 1.1 Ă— 1017 y ???? - 94Mo 96Zr 2.8% 2.0×1019y[3] ???? 3.348 96Mo This box: view â€˘ talk â€˘ edit

Zirconium rod

Zirconium (pronounced /z?r?ko?ni?m/ z?r-KOH-nee-?m) is a chemical element with the symbol Zr and atomic number 40. It is a lustrous, gray-white, strong transition metal that resembles titanium. Zirconium is used as an alloying agent due to its high resistance to corrosion. It is never found as a native metal; it is obtained mainly from the mineral zircon, which can be purified by chlorine. Zirconium was first isolated in an impure form in 1824 by JĂśns Jakob Berzelius.

Zirconium has no known biological role. Zirconium forms both inorganic and organometallic compounds such as zirconium dioxide and zirconocene dichloride, respectively. There are five naturally-occurring isotopes, three of which are stable. Short-term exposure to zirconium powder causes minor irritation, and inhalation of zirconium compounds can cause skin and lung granulomas.

Characteristics

Zirconium is a lustrous, grayish-white, soft, ductile, and malleable metal which is solid at room temperature, though it becomes hard and brittle at lower purities.^[4][5] In powder form, zirconium is highly flammable, but the solid form is far less prone to igniting. Zirconium is highly resistant to corrosion by alkalis, acids, salt water, and other agents.^[6] However, it will dissolve in hydrochloric and sulfuric acid, especially when fluorine is present.^[7] Alloys with zinc become magnetic below 35 K.^[6]

The melting point of zirconium is at 1855°C, and the boiling point is at 4409°C.^[6] Zirconium has an electronegativity of 1.33 on the Pauling scale. Of the elements within d-block, zirconium has the fourth lowest electronegativity after yttrium, lutetium, and hafnium.^[8]

Applications

Because of zirconium's excellent resistance to corrosion, it is often used as an alloying agent in materials that are exposed to corrosive agents, such as surgical appliances, explosive primers, vacuum tube getters and filaments. Zirconium dioxide (ZrO₂) is used in laboratory crucibles, metallurgical furnaces, and as a refractory material.^[6] Zircon (ZrSiO₄) is cut into gemstones for use in jewelry. Zirconium carbonate (3ZrO₂¡CO₂¡H₂O) was used in lotions to treat poison ivy, but this was discontinued as it caused bad skin reactions in some cases.^[4] 90% of all zirconium produced is used in nuclear reactors because of its low neutron-capture cross-section and resistance to corrosion.^[5][6] Zirconium alloys are used in space vehicle parts for their resistance to heat, an important quality given the extreme heat associated with atmospheric reentry.^[9] Zirconium is also a component in some abrasives, such as grinding wheels and sandpaper.^[10] Zirconium is used in weapons such as the BLU-97/B Combined Effects Bomb for incendiary effect. Zirconium in the oxidized form