HF
HF
Hf
hf.
Based on the Random House Dictionary, © Random House, Inc. 2012.
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| hf | |
| —abbreviation for | |
| half | |
| Hf | |
| —the chemical symbol for | |
| hafnium | |
| HF or h.f. | |
| —abbreviation for | |
| high frequency | |
| h.f. or h.f. | |
| —abbreviation for | |
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Hf
The symbol for the element hafnium.
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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hafnium  (hāf'nē-əm) Pronunciation Key
Symbol Hf A bright, silvery metallic element that occurs in zirconium ores. Because hafnium absorbs neutrons better than any other metal and is resistant to corrosion, it is used to control nuclear reactions. Atomic number 72; atomic weight 178.49; melting point 2,220°C; boiling point 5,400°C; specific gravity 13.3; valence 4. See Periodic Table. |
| Hf
The symbol for hafnium. |
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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| Hf hafnium |
HF
|
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Hf
chemicalchemical element (atomic number 72), metal of Group IVb of the periodic table. It is a ductile metal with a brilliant silvery lustre. The Dutch physicist Dirk Coster and the Hungarian-Swedish chemist George Charles de Hevesy discovered (1923) hafnium in Norwegian and Greenland zircons by analyzing their X-ray spectra. They named the new element for Copenhagen (in New Latin, Hafnia), the city in which it was discovered. Hafnium is dispersed in the Earth's crust to the extent of three parts per million and is invariably found in zirconium minerals up to a few percent compared with zirconium. Altered zircons, like some alvites and cyrtolites, products of residual crystallization, show greater percentages of hafnium (up to 17 percent hafnium oxide in cyrtolite from Rockport, Mass., U.S.). Commercial sources of hafnium-bearing zirconium minerals are found in beach sands and river gravel in the United States (principally Florida), Australia, Brazil, western Africa, and India. Hafnium vapour has been identified in the Sun's atmosphere.
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