Question

what is allotrophy.state the reasons of allotropy.

Answer 1

Allotropy is the property of some chemical elements to be able to take two or more different forms, where the atoms are arranged differently by chemical bonds. The forms are known as allotropes of that element. The phenomenon of allotropy is sometimes also called allotropism. For example, carbon has two common allotropes: diamond, where the carbon atoms are bonded together in a tetrahedral lattice arrangement, and graphite, where the carbon atoms are bonded together in sheets of a hexagonal lattice.

The word allotropy comes from the Greek allos, meaning "other", and tropos, "manner".

Allotropy refers only to different forms of an element within the same phase or state of matter (i.e. different solid, liquid or gas forms). Changes of state (between solid, liquid and gas) are not considered allotropy. Some elements have allotropes that persist in different phases - for example, the two allotropes of oxygen (dioxygen, O2, and ozone, O3), can both exist in the solid, liquid and gaseous states. Other elements maintain distinct allotropes only in some phases - for example phosphorus has many solid allotropes, which all revert to the same P4 form when melted to the liquid state.

Answer 2

polymorphism occurring in elements is called allotropy.

e.g:- diamond, graphite and fullerene are allotropic form of carbon.