Hf
Hafnium
Z 72 178.486 g/molTransition Metal
Nucleus
72 Protons
106 Neutrons
72 Electrons (4 Valence)
Shell distribution: K2 • L8 • M18 • N32 • O10 • P2 • Q0
Electron Configuration
Energy
7p
6d
5f
7s
6p
5d
4f
6s
5p
4d
5s
4p
3d
4s
3p
3s
2p
2s
1s
[Xe]4f145d26s2
Oxidation States
CommonRare
0
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Radii
Empirical
155 pm1.55 Å
Calculated
208 pm2.08 Å
Covalent
175±10 pm1.75±0.1 Å
Van der Waals
212 pm2.12 Å
IonicHf4+
71 pm0.71 Å
Crystal Structure
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Hexagonal close-packedStandard state
Pearson symbol
hP2
Space group
P63/mmc No. 194
Density
13.31 g/cm³