Hafnium

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Hafnium
Hf
In situ availability:
Necessity:
Atomic number: 72
Atomic mass: 178.49
group: 4
period: 6
normal phase: Solid
series: Transition Metals
density: 13.31 g/cm3
melting point: 2506K,
2233°C,
4051°F
boiling point: 4876K,
4603°C,
8317°F
YZrNb
Lu ← Hf → Ta
AcRfDb
Atomic radius (pm): 155
Bohr radius (pm): 208
Covalent radius (pm): 150
Van der Waals radius (pm):
ionic radius (pm): (+4) 83
1st ion potential (eV): 6.83
Electron Configuration
1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6 5d2
6s2
Electrons Per Shell
2, 8, 18, 32, 10, 2
Electronegativity: 1.3
Electron Affinity: ~0
Oxidation states: 4
Magnetism: ?
Crystal structure: Hexagonal

Hafnium is a Transition Metal in group 4.

It has a Hexagonal crystalline structure.

This element has 5 stable isotopes: 176, 177, 178, 179, and 180.

It forms part of the substance of the highest known melting point compound, tantalum-hafnium-carbide (Ta4HfC5), with a melting point of approximately 4215 C.[1] Hafnium is always found in nature mixed with zirconium whose ores often contain 1% to 5% hafnium.[2] Hafnium is used in nuclear fission reactor control rods because of its high neutron absorption cross section.



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  1. McGRAW-HILL ENCYCLOPEDIA OF Science & Technology, 8th Edition, (c)1997, vol 8, p 318
  2. CRC HANDBOOK of CHEMISTRY and PHYSICS, 64TH EDITION (1983-1984), p B-16