The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
Holmium is a rare earth element, one of the elements found in Row 6 of the periodic table between Groups 2 and 3. Its atomic number is 67, its atomic mass is 164.9303, and its chemical symbol is Ho.
Holmium is a silvery metal that is soft, ductile, and malleable. It has a melting point of 2,680°F (1,470°C), a boiling point of 4,930°F (2,720°C), and a density of 8.803 grams per cubic centimeter. It tends to be chemically stable at room temperature, but becomes more active at higher temperatures when, for example, it reacts with oxygen to form holmium oxide (Ho2O3).
The abundance of holmium in the Earth's crust is estimated to be about 0.7-1.2 parts per million, making it less common than most other rare earth elements, but more common than some familiar elements, such as iodine, silver, mercury, and gold. The most common ores of holmium are monazite and gadolinite. Holmium is extracted from its ores by heating calcium metal with holmium fluoride: 3Ca + 2HoF3 3CaF2 + 2 Ho.
Holmium was discovered in 1879 by the Swedish chemist Per Teodor Cleve (1840-1905). Cleve found the new element in a mineral called ytterite that had been discovered nearly a century earlier by a Swedish army officer, Carl Axel Arrhenius (1757- 1824). Ytterite was the subject of considerable research on the part of chemists and mineralogists and was eventually to yield nine new elements. Cleve named the new element after his birthplace, Stockholm.
Holmium has very few practical purposes, one exception being in the manufacture of specialized types of laser. Holmium lasers are now used to some extent in eye surgery where they are used to treat glaucoma and reduce abnormal eye pressure.