Hafnium

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Hafnium, 72Hf
Template:Infobox element/symbol-to-top-image/alt
Hafnium
Pronunciation/ˈhæfniəm/ (HAF-nee-əm)
Appearancesteel gray
Standard atomic weight Ar, std(Hf)178.49(2)[1]
Mass numberHf:
Hafnium in the periodic cairt
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gowd Mercur (element) Thallium Leid (element) Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium
Zr

Hf

Rf
lutetiumhafniumtantalum
Atomic nummer (Z)72
Groupgroup 4
Periodperiod 6
Blockd-block
Element category  Transeetion metal
Electron confeeguration[Xe] 4f14 5d2 6s2
Electrons per shell2, 8, 18, 32, 10, 2
Pheesical properties
Phase at STPsolit
Meltin pynt2506 K ​(2233 °C, ​4051 °F)
Bylin pynt4876 K ​(4603 °C, ​8317 °F)
Density (near r.t.)13.31 g/cm3
when liquid (at m.p.)12 g/cm3
Heat o fusion27.2 kJ/mol
Heat o vapourisation571 kJ/mol
Molar heat capacity25.73 J/(mol·K)
Vapour pressur
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 2689 2954 3277 3679 4194 4876
Atomic properties
Oxidation states−2, +1, +2, +3, +4 (an amphoteric oxide)
ElectronegativityPauling scale: 1.3
Atomic radiusempirical: 159 pm
Covalent radius175±10 pm
Colour lines in a spectral range
Spectral lines o hafnium
Ither properties
Naitural occurrenceHf: Primordial
Creestal structurhexagonal close-packed (hcp)
Hexagonal close packed creestal structur for hafnium
Speed o soond thin rod3010 m/s (at 20 °C)
Thermal expansion5.9 µm/(m·K) (at 25 °C)
Thermal conductivity23.0 W/(m·K)
Electrical resistivity331 n Ω·m (at 20 °C)
Magnetic orderinparamagnetic[2]
Young's modulus78 GPa
Shear modulus30 GPa
Bulk modulus110 GPa
Poisson ratio0.37
Mohs haurdness5.5
Vickers haurdness1760 MPa
Brinell haurdness1700 MPa
CAS Nummer7440-58-6
History
PredictionDmitri Mendeleev (1869)
DiskiveryDirk Coster an George de Hevesy (1922)
First isolationDirk Coster an George de Hevesy (1922)
Main isotopes o hafnium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct
172Hf syn 1.87 y ε 172Lu
174Hf 0.162% 2×1015 y α 170Yb
176Hf 5.206% - (α) 172Yb
177Hf 18.606% - (α) 173Yb
178Hf 27.297% - (α) 174Yb
178m3Hf syn 31 y IT 178Hf
179Hf 13.629% - (α) 175Yb
180Hf 35.1% - (α) 176Yb
182Hf trace 8.9×106 y β 182Ta
Decay modes in parentheses are predictit, but hae nae yet been observed
| references

Hafnium is a chemical element wi the seembol Hf an atomic nummer 72. A lustrous, sillery gray, tetravalent transeetion metal, hafnium chemically resembles zirconium an is foond in zirconium minerals. Its existence wis predictit bi Dmitri Mendeleev in 1869. Hafnium wis the penultimate stable isotope element tae be discovered (rhenium wis identified twa year later). Hafnium is named efter Hafnia, the Latin name for Copenhagen, whaur it wis discovered.

References[eedit | eedit soorce]

  1. Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305. Cite uses deprecated parameter |displayauthors= (help)
  2. Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.