Template:Infobox hafnium

Hafnium
72Hf
Zr ↑ Hf ↓ Rf Periodic table lutetium ← hafnium → tantalum
Appearance
steel gray
General properties
Name, symbol, number	hafnium, Hf, 72
Pronunciation	/ˈhæfniəm/ HAF-nee-əm
Element category	transition metal
Group, period, block	4, 6, d
Standard atomic weight	178.49
Electron configuration	[Xe] 4f14 5d2 6s2 2, 8, 18, 32, 10, 2
History
Naming	after Hafnia. Latin for: Copenhagen, where it was discovered
Prediction	Dmitri Mendeleev (1869)
Discovery	Dirk Coster and George de Hevesy (1922)
First isolation	Dirk Coster and George de Hevesy (1922)
Physical properties
Phase	solid
Density (near r.t.)	13.31 g·cm−3
Liquid density at m.p.	12 g·cm−3
Melting point	2506 K, 2233 °C, 4051 °F
Boiling point	4876 K, 4603 °C, 8317 °F
Heat of fusion	27.2 kJ·mol−1
Heat of vaporization	571 kJ·mol−1
Molar heat capacity	25.73 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 2689 2954 3277 3679 4194 4876
Atomic properties
Oxidation states	4, 3, 2 (amphoteric oxide)
Electronegativity	1.3 (Pauling scale)
Ionization energies	1st: 658.5 kJ·mol−1
	2nd: 1440 kJ·mol−1
	3rd: 2250 kJ·mol−1
Atomic radius	159 pm
Covalent radius	175±10 pm
Miscellanea
Crystal structure	hexagonal close-packed
Magnetic ordering	paramagnetic
Electrical resistivity	(20 °C) 331 nΩ·m
Thermal conductivity	23.0 W·m−1·K−1
Thermal expansion	(25 °C) 5.9 µm·m−1·K−1
Speed of sound (thin rod)	(20 °C) 3010 m·s−1
Young's modulus	78 GPa
Shear modulus	30 GPa
Bulk modulus	110 GPa
Poisson ratio	0.37
Mohs hardness	5.5
Vickers hardness	1760 MPa
Brinell hardness	1700 MPa
CAS registry number	7440-58-6
Most stable isotopes
Main article: Isotopes of hafnium
iso NA half-life DM DE (MeV) DP 172Hf syn 1.87 y ε 0.350 172Lu 174Hf 0.162% 2×1015 y α 2.495 170Yb 176Hf 5.206% 176Hf is stable with 104 neutrons 177Hf 18.606% 177Hf is stable with 105 neutrons 178Hf 27.297% 178Hf is stable with 106 neutrons 178m3Hf syn 31 y IT 2.446 178Hf 179Hf 13.629% 179Hf is stable with 107 neutrons 180Hf 35.1% 180Hf is stable with 108 neutrons 182Hf trace 8.9×106 y β− 0.373 182Ta

References

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