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Hafnium |
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Pronunciation | (HAF-nee-əm) |
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Appearance | steel gray |
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Standard atomic weight Ar, std(Hf) | 7002178490000000000♠178.49(2)[1] |
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Hafnium in the periodic cairt |
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Zr ↑ Hf ↓ Rf |
lutetium ← hafnium → tantalum |
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Atomic nummer (Z) | 72 |
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Group | group 4 |
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Period | period 6 |
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Block | d-block |
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Element category | Transeetion metal |
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Electron confeeguration | [Xe] 4f14 5d2 6s2 |
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Electrons per shell | 2, 8, 18, 32, 10, 2 |
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Pheesical properties |
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Phase at STP | solit |
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Meltin pynt | 2506 K (2233 °C, 4051 °F) |
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Bylin pynt | 4876 K (4603 °C, 8317 °F) |
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Density (near r.t.) | 13.31 g/cm3 |
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when liquid (at m.p.) | 12 g/cm3 |
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Heat o fusion | 27.2 kJ/mol |
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Heat o vapourisation | 571 kJ/mol |
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Molar heat capacity | 25.73 J/(mol·K) |
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Vapour pressur
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
2689 |
2954 |
3277 |
3679 |
4194 |
4876 |
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Atomic properties |
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Oxidation states | −2, +1, +2, +3, +4 (an amphoteric oxide) |
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Electronegativity | Pauling scale: 1.3 |
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Atomic radius | empirical: 159 pm |
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Covalent radius | 175±10 pm |
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Spectral lines o hafnium |
Ither properties |
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Naitural occurrence | primordial |
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Creestal structur | hexagonal close-packed (hcp) |
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Speed o soond thin rod | 3010 m/s (at 20 °C) |
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Thermal expansion | 5.9 µm/(m·K) (at 25 °C) |
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Thermal conductivity | 23.0 W/(m·K) |
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Electrical resistivity | 331 n Ω·m (at 20 °C) |
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Magnetic orderin | paramagnetic[2] |
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Young's modulus | 78 GPa |
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Shear modulus | 30 GPa |
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Bulk modulus | 110 GPa |
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Poisson ratio | 0.37 |
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Mohs haurdness | 5.5 |
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Vickers haurdness | 1760 MPa |
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Brinell haurdness | 1700 MPa |
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CAS Nummer | 7440-58-6 |
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History |
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Prediction | Dmitri Mendeleev (1869) |
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Diskivery | Dirk Coster an George de Hevesy (1922) |
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First isolation | Dirk Coster an George de Hevesy (1922) |
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Main isotopes o hafnium |
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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 |
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Decay modes in parentheses are predictit, but hae nae yet been observed |
| references |