Chemicool

Hf

72

178.49
Hafnium
General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles

General
Name Hafnium Symbol Hf
atomic number 72 Atomic weight 178.49
Density @ 293 K 13.2 g/cm3 Atomic volume 13.6 cm3/mol
Group Trans. Met. discovered 1923

States
state (s, l, g) s
melting point 2495.2 K boiling point 4723 K
Heat of fusion 24.060 kJ/mol Heat of vaporization 575.0 kJ/mol
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Energies
1st ionization energy 680 kJ/mole electronegativity 1.3
2nd ionization energy 1440 kJ/mole electron affinity 0 kJ/mole
3rd ionization energy 2250 kJ/mole Specific heat 0.14 J/gK
heat atomization 619 kJ/mole atoms

Oxidation & Electrons
Shells 2,8,18,32,10,2 electron configuration [Xe] 4f14 5d2 6s2
minimum oxidation number 0 maximum oxidation number 4
min. common oxidation no. 0 max. common oxidation no. 4
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Appearance & Characteristics
structure hcp: hexagonal close pkd color silvery
uses nuclear control rods toxicity
hardness mohs characteristics hard

Reactions
reaction with air mild, w/ht, = HfO2 reaction with 6M HCl none
reaction with 6M HCl none reaction with 15M HNO3 passivated
reaction with 6M NaOH none
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Other Forms
number of isotopes 6 hydride(s) HfH2
oxide(s) HfO2 chloride(s) HfCl3 HfCl4

Radius
ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius 159 pm ionic radius (1+ ion) pm
ionic radius (2+ ion) pm ionic radius (3+ ion) pm
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Conductivity
thermal conductivity 23.2 J/m-sec-deg electrical conductivity 28.49 1/mohm-cm
polarizability 16.2 A^3

Abundance
source Zircon (silicate) rel. abund. solar system -0.812 log
abundance earth's crust 0.4 log cost, pure 120 $/100g
cost, bulk $/100g
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