• WordNet 3.6
    • n allotropism the phenomenon of an element existing in two or more physical forms
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Webster's Revised Unabridged Dictionary
    • n Allotropism (Chem) The property of existing in two or more conditions which are distinct in their physical or chemical relations.☞ Thus, carbon occurs crystallized in octahedrons and other related forms, in a state of extreme hardness, in the diamond; it occurs in hexagonal forms, and of little hardness, in black lead; and again occurs in a third form, with entire softness, in lampblack and charcoal. In some cases, one of these is peculiarly an active state, and the other a passive one. Thus, ozone is an active state of oxygen, and is distinct from ordinary oxygen, which is the element in its passive state.
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Century Dictionary and Cyclopedia
    • n allotropism Allotropical variation; allotropy.
    • n allotropism The occurrence of more than one form of a chemical element with difference in physical properties is explained, in the light of the atomic theory, as depending on a difference in the number, and possibly in the arrangement, of the atoms which go to make up the molecule. Thus it is believed that in the more common form of oxygen there are two, but in the allotropic ozone three, atoms to the molecule.
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Webster's Revised Unabridged Dictionary
Gr. other + direction, way, to turn: cf. F. allotropie,


In literature:

He tells me that Liebig is full of ozone, i.e., of allotropic oxygen.
"Faraday As A Discoverer" by John Tyndall
Perhaps they have not studied the mystery of allotropism in the emotions of the human heart.
"Elsie Venner" by Oliver Wendell Holmes, Sr.
It is easy to call these changes by the name allotropism, but not the less do they confound our hasty generalizations.
"Medical Essays" by Oliver Wendell Holmes, Sr.
It occurs likewise in several allotropic states as graphite, plumbago, charcoal, anthracite, etc.
"A System of Instruction in the Practical Use of the Blowpipe" by Anonymous
I am a gentleman in allotropic form'; that was as much as I ever heard him say.
"Grey Roses" by Henry Harland
Further, the allotropic modifications of elements and the isomerism of compounds increased the difficulties.
"Scientific American Supplement, No. 643, April 28, 1888" by Various
Only such forms, however, as have different energy contents are properly called allotropic forms.
"An Elementary Study of Chemistry" by William McPherson
This element exists in several allotropic forms, which have very different electric properties.
"On Laboratory Arts" by Richard Threlfall
Just let me tell you, to use a very hard word, that we call the diamond an "allotropic" form of carbon.
"The Story of a Tinder-box" by Charles Meymott Tidy
Another element occurring in allotropic forms is sulphur, of which many forms have been described.
"Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1" by Various

In science:

Historically, any allotrope based on the element carbon has been classed as organic, but a new carbon allotrope stretches that definition.
Route to Room-Temperature Superconductivity from a Practical Point of View
While the importance of sp2 structure is by now confirmed, a lot of interest is growing around sp carbon allotropes, named carbynes.
Ab initio investigation of the groundstate, electronic, and optical properties of polyyne and cumulene prototypes
Although the existence and the properties of three dimensional allotrope, graphite containing weakly coupled stacks of graphene layers were well known , the experimental realization of a monolayer graphene, brought forth a completely different set of novel properties [3, 4].
A Systematic Study of Electronic Structure from Graphene to Graphane
These experiments could hold the key to answering fundamental questions about quantum mechanics and the nature of the quantum-classical transition and more. C60 , the third allotropic form of carbon was discovered in 1985 by Kroto and colleagues.
Quantum interference of molecules -- probing the wave nature of matter
As a consequence, carbon can exist in many stable allotropic forms, characterized by the different relative orientions of the carbon atoms.
Modeling disorder in graphene