Hafnium

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

• Web Elements: Website

• 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