|
Search over 100 encyclopedias and dictionaries: |
Research categories | Follow us on Twitter |
Research categories
View all topics in the newsView all reference sources at Encyclopedia.com |
|||
exclusion principle
exclusion principle physical principle enunciated by Wolfgang Pauli in 1925 stating that no two electrons in an atom can occupy the same energy state simultaneously. The energy states, or levels, in an atom are described in the quantum theory by various values of four different quantum numbers; the exclusion principle holds that no two electrons can have the same four quantum numbers in an atom. One of these quantum numbers describes one of the two possible directions for the electron's intrinsic spin. As a result of the exclusion principle, two electrons that are in the same energy level as described by the other three quantum numbers are differentiated from each other because they have opposite spins. This principle applies not only to atoms but to other systems containing particles as well, and it applies not only to electrons but also to a large class of particles collectively known as fermions (see elementary particles ). |
|
|
Cite this article
"exclusion principle." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>. "exclusion principle." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1E1-exclusio.html "exclusion principle." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-exclusio.html |
|
exclusion principle
exclusion principle Basic law of quantum mechanics, proposed by Wolfgang Pauli in 1925, stating no two electrons in an atom can possess the same energy and spin. More precisely, the set of four quantum numbers characterizing certain elementary particles called fermions must be unique.
|
|
|
Cite this article
"exclusion principle." World Encyclopedia. 2005. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>. "exclusion principle." World Encyclopedia. 2005. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1O142-exclusionprinciple.html "exclusion principle." World Encyclopedia. 2005. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-exclusionprinciple.html |
|
exclusion principle
exclusion principle A principle introduced in 1934 by the Russian ecologist G. F.Gause (1910–86), that two species cannot coexist in the same locality if they have identical ecological requirements.
|
|
|
Cite this article
MICHAEL ALLABY. "exclusion principle." A Dictionary of Ecology. 2004. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "exclusion principle." A Dictionary of Ecology. 2004. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1O14-exclusionprinciple.html MICHAEL ALLABY. "exclusion principle." A Dictionary of Ecology. 2004. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-exclusionprinciple.html |
|
exclusion principle
exclusion principle A principle, introduced by G. F. Gause, that two species cannot coexist in the same locality if they have identical ecological requirements.
|
|
|
Cite this article
MICHAEL ALLABY. "exclusion principle." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "exclusion principle." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1O7-exclusionprinciple.html MICHAEL ALLABY. "exclusion principle." A Dictionary of Plant Sciences. 1998. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O7-exclusionprinciple.html |
|
exclusion principle
exclusion principle See COMPETITIVE-EXCLUSION PRINCIPLE.
|
|
|
Cite this article
MICHAEL ALLABY. "exclusion principle." A Dictionary of Zoology. 1999. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "exclusion principle." A Dictionary of Zoology. 1999. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1O8-exclusionprinciple.html MICHAEL ALLABY. "exclusion principle." A Dictionary of Zoology. 1999. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-exclusionprinciple.html |
|
Search over 100 encyclopedias and dictionaries:
HighBeam™ Research, Inc. © Copyright 2012. All rights reserved.
The Encyclopedia.com advertising network includes:
