allotrope

(noun)

A different form of an element in its natural state. For instance, oxygen is found predominantly in two forms: O2 and O3 (ozone).

Related Terms

  • phosphate
  • depolymerization
  • octasulfur
  • adenosine triphosphate
  • covalent network solid
  • diamond
  • carbide
  • covalent bond

(noun)

Any form of a pure element that has a distinctly different molecular structure to another form of the same element.

Related Terms

  • phosphate
  • depolymerization
  • octasulfur
  • adenosine triphosphate
  • covalent network solid
  • diamond
  • carbide
  • covalent bond

(noun)

Any form of a pure element that has a distinctly different molecular structure.

Related Terms

  • phosphate
  • depolymerization
  • octasulfur
  • adenosine triphosphate
  • covalent network solid
  • diamond
  • carbide
  • covalent bond

Examples of allotrope in the following topics:

  • Properties of Sulfur

    • Sulfur burns with blue flame, is insoluble in water, and forms polyatomic allotropes.
    • Sulfur is found is different polyatomic allotropic forms.
    • The best-known allotrope is octasulfur, cyclo-S8.
    • The density of sulfur is about 2 g/cm3, depending on the allotrope.
    • All of sulfur's stable allotropes are excellent electrical insulators.
  • Allotropes of Carbon

    • Various allotropes of carbon exhibit different properties and find applications in a variety of fields.
    • There are several allotropes of carbon.
    • Diamond is probably the most well known carbon allotrope.
    • Graphite is another allotrope of carbon; unlike diamond, it is an electrical conductor and a semi-metal.
    • Carbon nanomaterials make up another class of carbon allotropes.
  • Properties of Carbon

    • Carbon has several allotropes, or different forms in which it exists.
    • Interestingly, carbon allotropes span a wide range of physical properties: diamond is the hardest naturally occurring substance, and graphite is one of the softest known substances.
    • Allotropes of carbon are not limited to diamond and graphite, but also include buckyballs (fullerenes), amorphous carbon, glassy carbon, carbon nanofoam, nanotubes, and others.
    • Some allotropes of carbon: a) diamond, b) graphite, c) lonsdaleite, d–f) fullerenes (C60, C540, C70); g) amorphous carbon, h) carbon nanotube.
  • Properties of Phosphorus

    • Phosphorus is found in its elemental form as different allotropes, none of which are stable in the presence of oxygen.
    • Phosphorus exists in several forms (allotropes) that exhibit strikingly different properties.
    • The two most common allotropes are white phosphorus and red phosphorus.
    • Another allotrope is diphosphorus; it contains a phosphorus dimer as a structural unit and is highly reactive.
    • White phosphorus is the least stable, the most reactive, the most volatile, the least dense, and the most toxic of the allotropes.
  • Covalent Crystals

    • Graphite is an allotrope of carbon.
    • In this allotrope, each atom of carbon forms three covalent bonds, leaving one electron in each outer orbital delocalized, creating multiple "free electrons" within each plane of carbon.
    • Diamond is also an allotrope of carbon.
    • These two allotropes of carbon are covalent network solids which differ in the bonding geometry of the carbon atoms.
  • Standard States and Standard Enthalpy Changes

    • Standard states for atomic elements are given in terms of the most stable allotrope for each element.
    • For example, white tin and graphite are the most stable allotropes of tin and carbon, respectively.
    • White tin (on the left) is the most stable allotrope of tin, and is used as its standard state for thermodynamic calculations.
  • Molecular Crystals

    • For example, solid phosphorus can crystallize in different allotropes called "white", "red" and "black" phosphorus.
    • Although white phosphorus is an insulator, the black allotrope, which consists of layers extending over the whole crystal, does conduct electricity.
    • The structural transitions in phosphorus are reversible: upon releasing high pressure, black phosphorus gradually converts into the red allotrope, and by vaporizing red phosphorus at 490 °C in an inert atmosphere and condensing the vapor, covalent red phosphorus can be transformed back into the white molecular solid.
    • However, they can convert into covalent allotropes having atomic chains extending all through the crystal.
  • Fused Benzen Ring Compounds

    • Such a carbon allotrope exists and is called graphite.
    • Another well-characterized carbon allotrope is diamond.
    • These materials represent a third class of carbon allotropes.
  • Ozone

    • It is an allotrope of oxygen that is much less stable than the diatomic allotrope (O2), breaking down with a half life of about half an hour in the lower atmosphere to O2.
  • Elemental Boron

    • Several allotropes of boron exist.
Subjects
  • Accounting
  • Algebra
  • Art History
  • Biology
  • Business
  • Calculus
  • Chemistry
  • Communications
  • Economics
  • Finance
  • Management
  • Marketing
  • Microbiology
  • Physics
  • Physiology
  • Political Science
  • Psychology
  • Sociology
  • Statistics
  • U.S. History
  • World History
  • Writing

Except where noted, content and user contributions on this site are licensed under CC BY-SA 4.0 with attribution required.