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Allotropy or allotropism (from Ancient Greek ἄλλος (allos) 'other' and τρόπος (tropos) 'manner, form') is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements. Allotropes are different structural modifications of an element: the atoms of the ...
Carbon is capable of forming many allotropes (structurally different forms of the same element) due to its valency (tetravalent). Well-known forms of carbon include diamond and graphite. In recent decades, many more allotropes have been discovered and researched, including ball shapes such as buckminsterfullerene and sheets such as graphene.
Elements including metals may exhibit polymorphism. Allotropy is the term used when describing elements having different forms and is used commonly in the field of metallurgy. Some (but not all) allotropes are also polymorphs. For example iron has three allotropes that are also polymorphs. Alpha-iron, which exists at room temperature, has a bcc ...
In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states of matter: solid, liquid, and gas, and in rare cases, plasma.
At atmospheric pressure, three allotropic forms of iron exist, depending on temperature: alpha iron (α-Fe, ferrite), gamma iron (γ-Fe, austenite), and delta iron (δ-Fe). At very high pressure, a fourth form exists, epsilon iron (ε-Fe, hexaferrum). Some controversial experimental evidence suggests the existence of a fifth high-pressure form ...
A fullerene is an allotrope of carbon whose molecules consist of carbon atoms connected by single and double bonds so as to form a closed or partially closed mesh, with fused rings of five to seven atoms. The molecules may have hollow sphere - and ellipsoid -like forms, tubes, or other shapes. Fullerenes with a closed mesh topology are ...
Allotropes of sulfur. Cyclo -octasulfur (cyclo - S8 or cyclooctasulfane), the most prevalent allotrope of sulfur in nature. The element sulfur exists as many allotropes. In number of allotropes, sulfur is second only to carbon. [1] In addition to the allotropes, each allotrope often exists in polymorphs (different crystal structures of the same ...
Transition temperature. In crystallography, the transition temperature is the temperature at which a material changes from one crystal state (allotrope) to another. [1] More formally, it is the temperature at which two crystalline forms of a substance can co-exist in equilibrium.