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Article: Holmium
- Article from:
- Chemistry: Foundations and Applications
- Author:
CopyrightCOPYRIGHT 2004 The Gale Group, Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Holmium
melting point:
1,461
°
C
boiling point:
2,720
°
C
density:
8.803 g/cm
3
most common ions:
Ho
3+
A member of the
lanthanide
, or rare earth, series of elements, holmium is a gray, somewhat shiny, soft
metal
. It is usually found in minerals containing several of the lanthanides. Because the
rare earths
all have the same outer electron shell configuration (6s
2
), their chemical properties are very similar, making it difficult to separate them from one another in the minerals in which they are usually complexed. They are best separated via repeated ion-exchange purification, a process developed in the United States during the 1940s. Although several of the rare ...