* Hafnium is a member of the transition metals family:
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HAFNIUM / Hf / 72
A lustrous, silvery, ductile metal that resists corrosion by
forming an oxide layer. Six isotopes are found in nature.
Hf<180/72>: 35%
Hf<178/72>: 27.5%
Hf<177/72>: 18.5%
Hf<179/72>: 13.5%
Hf<176/72>: 5%
Hf<174/72>: 0.16%
All are stable, except for Hf<174/72>, which has a long half-life
of 2E15 years.
atomic weight: 178.49
abundance: 45th
density: 13.3 gm/cc
melting point: 2,227 C
boiling point: 4,602 C
valence: 4
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Although hafnium is a surprisingly common element, it took a long time to find because it is generally found in association with zirconium, and it is troublesome to separate the two since their properties are very similar. Production of hafnium is in the tens of tonnes a year, and so it is unsurprisingly expensive. It is a good neutron absorber, mostly due to the trace barely-unstable Hf<174/72> isotope, and is often used in nuclear reactor control rods, where its high melting point and resistance to corrosion are useful as well. It is also used in some high-temperature alloys, ceramics, and glasses.
