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Atomic Number	72

Atomic Symbol	Hf

Atomic Weight	178.49 amu

Group	Transition, 4

Form	Solid

Density @ STP	13.3 g/cm³

Melting Point	2233 °C (4051.4 °F, 2506.15 °K)

Boiling Point	4603 °C (8317.4 °F, 4876.15 °K)

Heat of Fusion	27.2 kJ/mol

Heat of Vaporization	630 kJ/mol

First Ionization Potential	6.82507 eV

Electronegativity (on Pauling scale	1.3

Specific Heat Capacity	0.144 J/g K

Ground State Electron Configuration	5d² 6s²

Oxidation State(s)	+4

Stable Isotopes and Natural Abundance on Earth	¹⁷⁴Hf, 0.162%; ¹⁷⁶Hf, 5.206%; ¹⁷⁷Hf, 18.606%; ¹⁷⁸Hf, 27.297%; ¹⁷⁹Hf, 13.629%; ¹⁸⁰Hf, 35.100%

Selected Radioisotopes	¹⁷²Hf

Atomic Radius	208 om

Crystal Structure	Hexagonal

Discovered by	Coster; Charles von Hevesy, 1923