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.
Hafnium, 72 Hf Hafnium Pronunciation (HAF -nee-əm ) Appearance steel gray Standard atomic weight A r, std (Hf) 7002178490000000000♠ 178.49(2)[1] Hafnium in the periodic cairt Zr ↑Hf ↓Rf lutetium ← hafnium → tantalum
Atomic nummer (Z ) 72 Group group 4 Period period 6 Block d-block Element category Transeetion metalElectron confeeguration [Xe ] 4f14 5d2 6s2 Electrons per shell 2, 8, 18, 32, 10, 2 Pheesical properties Phase at STP solit Meltin pynt 2506 K (2233 °C, 4051 °F) Bylin pynt 4876 K (4603 °C, 8317 °F) Density (near r.t. ) 13.31 g/cm3 when liquid (at m.p. ) 12 g/cm3 Heat o fusion 27.2 kJ/mol Heat o vapourisation 571 kJ/mol Molar heat capacity 25.73 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) Electronegativity Pauling scale: 1.3 Atomic radius empirical: 159 pm Covalent radius 175±10 pm Colour lines in a spectral range Spectral lines o hafnium Ither properties Naitural occurrence primordial Creestal structur hexagonal close-packed (hcp) Speed o soond thin rod 3010 m/s (at 20 °C) Thermal expansion 5.9 µm/(m·K) (at 25 °C) Thermal conductivity 23.0 W/(m·K) Electrical resistivity 331 n Ω·m (at 20 °C) Magnetic orderin paramagnetic[2] Young's modulus 78 GPa Shear modulus 30 GPa Bulk modulus 110 GPa Poisson ratio 0.37 Mohs haurdness 5.5 Vickers haurdness 1760 MPa Brinell haurdness 1700 MPa CAS Nummer 7440-58-6 History Prediction Dmitri Mendeleev (1869) Diskivery Dirk Coster an George de Hevesy (1922) First isolation Dirk Coster an George de Hevesy (1922) Main isotopes o hafnium Isotope Abundance Hauf-life (t 1/2 ) Decay mode Product 172 Hfsyn 1.87 y ε 172 Lu174 Hf0.162% 2×1015 y α 170 Yb176 Hf5.206% - (α) 172 Yb177 Hf18.606% - (α) 173 Yb178 Hf27.297% - (α) 174 Yb178m3 Hfsyn 31 y IT 178 Hf179 Hf13.629% - (α) 175 Yb180 Hf35.1% - (α) 176 Yb182 Hftrace 8.9×106 y β− 182 Ta
Decay modes in parentheses are predictit, but hae nae yet been observed | references
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