Hafnium

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Description

A shiny, ductile metallic element first identified in 1923. Hafnium has an abundance in the earth's crust of about 5 ppm. It is found in the minerals Zircon, cyrtolite, alvite, and malacon. Hafnium occurs naturally with Zirconium and the two metals are very difficult to separate. It is used as a neutron absorbing material in nuclear reactors, as a filament in lightbulbs and as a cathode in x-ray tubes. Hafnium is also used as an oxygen and nitrogen scavenger.

Synonyms and Related Terms

Hf; afnio (It.); Háfnio (Port.); hafnio (Esp.)

Risks

  • Toxic by inhalation.
  • Powder is explosive in air.
  • Sigma-Aldrich: SDS (powder)

Physical and Chemical Properties

Soluble in warm HCl and sulfuric acid. Resistant to weak acids and their salts.

Composition Hf (atomic no. 72)
CAS 7440-58-6
Mohs Hardness 5.5
Melting Point 2227-2233 C
Density 13.3 g/ml
Molecular Weight atomic wt = 178.49
Boiling Point 4602-4603 C

Resources and Citations

  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  • The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998