Basic chemistry

What is allotropy explain?

Allotropy definition?

We explain that what does allotropy means? with Allotropy definition and examples.

Allotropy definition and examples are listed here.In chemistry , mineralogy or, more broadly, in materials science, the term “allotropy” refers to the property that certain bodies enjoy under different varieties (generally denoted α, β, etc.).

These different varieties can be distinguished by:

  • their physical forms  ;
  • their atomic or molecular arrangements (types of bonds, crystalline structure);
  • their densities.

However, they have very similar chemical properties. The term “allotrope” was defined by the Swedish chemist Jons Jacob Berzelius early XIX th  century.

Attention, we speak of allotropy only in the case of different forms of the same element within the same phase ( solid , liquid , gas ). Thus, phase changes do not correspond to changes in allotropic form. For example, liquid oxygen and gaseous oxygen are not two allotropic forms.

Chemical elements and allotropic forms: sulfur, carbon …

allotropy definition and examples
allotropes of carbon

The chemical elements capable of forming a number of variable chemical bonds or of concatenation are those which have the most allotropic forms. Likewise, non-metals are more prone to allotropy than metals . Here are some examples :

  • For a long time sulfur held the record for the number of allotropic forms.
  • It is now overtaken by carbon , of which the two best-known allotropic forms are diamond ( transparent and hard crystal ) and graphite (black and soft solid with a graphene structure ). But there are other allotropic forms of carbon, less common:
  • lonsaleiteite;
  • chaoite;
  • the fullerenes ;
  • the carbon nanotubes ;
  • the glassy carbon , etc.
  • The phosphorus red, used for the manufacture of matches , is an allotrope of phosphorus.

Allotropic phenomena

The allotropic phenomenon occurs when chemical elements link their atoms in different ways, this causes these compounds to have different chemical properties.

Noble gases, being chemically inert, do not have allotropy.

Carbon allotropic phenomenon

Surely you have heard that carbon can be presented as graphite and diamond , but there are other forms such as fullerene , soot , nanotube (NCT).

Fullerene is used as an electrical conductor, for solar panels, as antioxidants, to neutralize viruses,

The carbon nanotubes , optical devices allow to manufacture higher quality can carry electrical currents hundred times larger than copper, they are 200 times stronger than steel.

Allotropic phenomenon of phosphorus

Phosphorus P 4 occurs in nature as:

  • White phosphorus , reacts quickly with oxygen, igniting easily at temperatures of 10 to 15 degrees below room temperature. That is why it is used a lot for war purposes. Small amounts of white phosphorus are used in pesticides and fireworks.
  • red phosphorus , much less reactive and toxic than white phosphorus. This is used for the production of matches (domestic)

Allotropic oxygen phenomenon

  • The 2 (dioxygen), is the most abundant, present in the earth ‘s atmosphere.
  • The 3 (ozone) is a highly reactive gas I bluish. It is used for medical purposes and for the purification and treatment of water.

Other allotropic phenomena

For sulfur:

  • Monoclinic sulfur, this form is less stable than rhombic sulfur, it is present in the form of fine, opaque needles.
  • rhombic sulfur, this is the most stable and most common allotropic form of sulfur. It appears in the form of yellow and transparent crystals.
  • amorphous sulfur is light brown in color and is formed by sudden cooling of liquid sulfur.

For antimony:

  • White antimony is very brittle, bluish-white in color with a characteristic metallic luster.
  • Yellow antimony, they are non-metallic and unstable forms
  • Black antimony, they are non-metallic and unstable forms

For polonium:

  • Alpha polonium
  • Beta polonium

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