actinide
American Heritage Dictionary:
Top
ac·ti·nide
(ăk'tə-nīd') 
n.
Any of a series of chemically similar, radioactive elements with atomic numbers ranging from 89 (actinium) through 103 (lawrencium).
n.
Any of a series of chemically similar, radioactive elements with atomic numbers ranging from 89 (actinium) through 103 (lawrencium).
[ACTIN(IUM) + -IDE.]
Britannica Concise Encyclopedia:
Top
actinide
Any of the series of 15 consecutive chemical elements in the periodic table from actinium to lawrencium (atomic numbers 89103). All are radioactive heavy metals; and only the first four (actinium, thorium, protactinium, and uranium) occur in nature in appreciable quantities. The other 11 (the transuranium elements) are unstable and are produced only artificially. Actinides are transition elements, so their atoms have similar configurations and similar physical and chemical behaviour; the most usual valences are 3 and 4.
For more information on actinide, visit Britannica.com.
Top
(ăk'tə-nī'd)
n.
n.
Any of a series of chemically similar radioactive elements with atomic numbers ranging from 89 (actinium) through 103 (lawrencium).
Post a question - any question - to the WikiAnswers community:
Copyrights:
American Heritage Dictionary
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
Read more
Britannica Concise Encyclopedia
Britannica Concise Encyclopedia. © 1994-2012 Encyclopædia Britannica, Inc. All rights reserved. Read more
Mentioned in
neptunium
(chemistry)
transactinide elements
(in chemistry)
berkelium
(chemistry)
protactinium
(chemistry)
rutherfordium
(chemistry)
» More