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.
Quick Facts Pronunciation, Appearance ...
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 metal Electron 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 hafniumIther 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
Iso tope
Abun dance
Hauf-life (t 1/2 )
Decay mode
Pro duct
172 Hf
syn
1.87 y
ε
172 Lu
174 Hf
0.162%
2× 1015 y
α
170 Yb
176 Hf
5.206%
-
(α )
172 Yb
177 Hf
18.606%
-
(α )
173 Yb
178 Hf
27.297%
-
(α )
174 Yb
178m3 Hf
syn
31 y
IT
178 Hf
179 Hf
13.629%
-
(α )
175 Yb
180 Hf
35.1%
-
(α )
176 Yb
182 Hf
trace
8.9× 106 y
β−
182 Ta
Decay modes in parentheses are predictit, but hae nae yet been observed | references
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