Examples of allotrope in the following topics:
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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 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.
-
- 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.
-
- 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.
-
- 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.
-
- Several allotropes of boron exist.