allotropy
The Columbia Encyclopedia, Sixth Edition | Date: 2008
allotropy [Gr.,=other form]. A chemical element is said to exhibit allotropy when it occurs in two or more forms in the same physical state; the forms are called allotropes. Allotropes generally differ in physical properties such as color and hardness; they may also differ in molecular structure or chemical activity, but are usually alike in most chemical properties. Diamond and graphite are two allotropes of the element carbon . Ozone is a chemically active triatomic allotrope of the element oxygen . Phosphorus , sulfur , and tin also exhibit allotropy. Many metals have allotropic crystalline forms that are stable at different temperatures. Polymorphism is an analogous phenomenon observed in chemical compounds.
Author not available, ALLOTROPY.,
The Columbia Encyclopedia, Sixth Edition 2008
The Columbia Encyclopedia, Sixth Edition. Copyright 2008 Columbia University Press
Related newspaper, magazine, and journal articles from HighBeam Research
|
Rigauku/USA.(Brief Article)
Instrument Business Outlook; 8/15/2001; 13 words
; Rigauku/USA has merged with its Molecular Structure subsidiary to form Rigaku/MSC
Read more
|
|
Ties have become more than ties: They're statements.(Originated from Knight-Ridder Newspapers)
Knight Ridder/Tribune News Service; 10/5/1995; Tasker, Fred; 1225 words
; These are the ties that blind. Well, some of them are. Others are actually rather staid. What sets them apart from their predecessors _ in the long and curious male tradition of spending two or three hours' pay at a whack to buy and then knot irritating strips of cloth around their necks for no
Read more
|
|
Understanding properties of polymer thin films. (News Briefs).(Brief Article)
Journal of Research of the National Institute of Standards and Technology; 3/1/2002; 228 words
; Polymer thin films have important applications in many industries. They are found, for example, in semiconductor devices, automobile coatings, and construction materials. The molecular structure at both the free and buried interfaces of thin films are critical to their performance, as they can
Read more
|
|
Tubing strengthening.(Pumps & Lines)
Designfax; 7/1/2004; 77 words
; This high-energy e-beam process cross-links polymer molecules to provide a permanent 3D molecular structure with high tensile strength, durability, and high temp-, creep-, fatigue- and abrasion-resistance, The molecular structure of cross-linked tubing retains shape memory so that it can be
Read more
|
|
RP improvements suggested.
Tooling & Production; 6/1/2000; 311 words
; NASA's Jet Propulsion Laboratory, Pasadena, CA, reports that several improvements have been proposed in the area of rapid prototyping. In rapid prototyping according to current practice, the polymeric material is one that has low molecular weight, little or no cross linking, and few (if any) active
Read more
|
|
Smurfit-Kappa invests in biodegradable packaging research.(NANOCLAY TECHNOLOGY)
Official Board Markets; 5/5/2007; 322 words
; According to Materials Recycling Week, a change in the molecular structure of nanoclays has been made by European Union (EU) researchers working with Smurfit-Kappa and British supermarket chain Sainsbury in developing a new recyclable and biodegradable biopolymer food packaging. The project is
Read more
|
|
Victorian research facility building world's largest parallel protein production facility.(NEWS Brief)
Bioscience Technology; 4/1/2005; 215 words
; The world's largest parallel protein purification workstation is to be housed at Monash University, improving Australian scientists' abilities to study the molecular structure and function of proteins. Victorian Bioinformatics Consortium Scientific Director and Monash University researcher Dr.
Read more
|
|
New additive helps cosmetics, lotions penetrate skin.(International)
Household & Personal Products Industry; 12/1/2007; 115 words
; * JAPAN: Nippon Fine Chemical Co. has developed an oil-based agent that helps hair care products and lotions penetrate hair and skin more easily. The new agent has a three-dimensional molecular structure, composed of dicarboxylic acid, which increases moisture retention and lubrication, and
Read more
|
 "The Birmingham Post (England)")
|
Hair offers cancer hope.(News)
The Birmingham Post (England); 3/4/1999; 139 words
; Hair could provide a new method of screening for breast cancer, scientists said yesterday. Researchers in Australia discovered that hair from women with breast cancer has a different molecular structure from that of healthy women. Hair from women carrying a gene associated with the disease also
Read more
|
|
Another first: DNA scientist gets his own genome map.(Front)
The Virginian Pilot; 6/1/2007; 216 words
; Byline: JUAN A. LOZANO HOUSTON -- By JUAN A. LOZANO The Associated Press HOUSTON - The Nobel Prize-winning scientist who helped discover the molecular structure of DNA has become the first person to receive his own personal genome map. The map, a breakdown of his DNA that shows illnesses he is
Read more
|
Related entries from encyclopedias, dictionaries, and thesauruses
|
allotropy
World Encyclopedia
allotropy Property of some chemical elements that enables them to exist in two or more distinct physical forms. Each form (an allotrope ...
Read more
|
|
ozone
The Columbia Encyclopedia, Sixth Edition
, an allotropic form of the chemical element oxygen (see allotropy ). Pure ozone is an unstable, faintly bluish gas with a characteristic fresh, penetrating odor. The gas has a density of 2.144 ...
Read more
|
|
|
diamond
The Columbia Encyclopedia, Sixth Edition
mineral, one of two crystalline forms of the element carbon (see allotropy ), the hardest natural substance known, used as a gem and in industry. Properties Diamonds crystallize in the isometric system ...
Read more
|
|
|
selenium
The Columbia Encyclopedia, Sixth Edition
... of the periodic table . In chemical activity and physical properties it resembles sulfur and tellurium. Selenium exhibits allotropy, appearing in a number of forms, including a red amorphous powder, a red crystalline material, and a gray crystalline metallike ...
Read more
|
|
|
phosphorus
World Encyclopedia
... phosphoric acid for detergents and fertilizers. Small amounts are used in insecticides and in matches. Phosphorus exhibits allotropy . Properties: at.no. 15; r.a.m. 30.9738; r.d. 1.82 (white), 2.34 (red); m.p. 44.1°C (111.38°F) (white); b.p. 280 ...
Read more
|