There are more than 400 varieties allotropic simple substances.However, the exact reason for the modification of this kind is still not revealed.In modifications of such molecules, usually a different number of atoms and the crystal lattice structure, and thereby vary the physical properties of these substances.Found allotropic modification arsenic, strontium, selenium, antimony, at high temperatures - iron and many other elements.Tendency to allotropy brighter manifested in non-metals.The exception is the halogens and the noble gases, and semi-metals.

allotropic modifications

- Phosphorus.We studied 11 allotropic modifications of phosphorus, including white, red and black.They all differ in physical properties.White phosphorus glows in the dark and can catch fire, while red is no
t flammable, and has no luminescence is not poisonous.
- Carbon.It has long been an established fact that diamond and coal during combustion to form carbon dioxide.It follows that they contain the same element - carbon.There are many forms of carbon atoms bind to each other, so it is impossible to say exactly the number of its modifications.The most famous are - graphite, diamond, carbine, lonsdalite carbon fullerenes.
- Sulphur.A similar contrast characterizes two varieties of sulfur molecules.The difference between the molecules of sulfur is that sulfur atoms constitute octavalent eight membered ring, and the molecules are arranged in a hexavalent linear chain of six sulfur atoms.Under normal conditions, all modifications passes into the rhombic sulfur.
- Oxygen.In the oxygen there are two allotropic modifications: oxygen and ozone.Oxygen is colorless and odorless.Ozone has a specific smell, pale purple flowers and a biocide.
- Bor.In more than 10 boron allotropic modifications.There amorphous boron in the form of brown powder and a black crystal.The physical properties of these materials are different.Since the reactivity of the amorphous boron is much higher than the crystalline.
- Silicon.Two pivotal modification of silicon - is amorphous and crystalline.There polycrystalline and monocrystalline silicon.The difference lies in the structure of their crystal lattices.
- Antimony.We studied four metallic and three amorphous allotropic modification of antimony: explosive, black and yellow.Metal modification exist at different pressures.From the most stable form of amorphous - silvery-white with a bluish tinge.