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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.
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.
Below 912 °C (1,674 °F), iron has a body-centered cubic (bcc) crystal structure and is known as α-iron or ferrite.It is thermodynamically stable and a fairly soft metal. α-Fe can be subjected to pressures up to ca. 15 GPa before transforming into a high-pressure form termed ε-Fe discussed below.
White phosphorus (left), red phosphorus (center left and center right), and violet phosphorus (right) White phosphorus and resulting allotropes Elemental phosphorus can exist in several allotropes, the most common of which are white and red solids.
Phase information is based on the work of G. C. Vezzoli, et al., as reviewed by David Young; as Young notes, "The literature on the allotropy of sulfur presents the most complex and confused situation of all the elements." [8] [9] Phase information are limited to ≤50 kbar and thus omitting metallic phases. [10]
Amorphous powder boron Boron (likely mixed allotropes). Boron can be prepared in several crystalline and amorphous forms. Well known crystalline forms are α-rhombohedral (α-R), β-rhombohedral (β-R), and β-tetragonal (β-T).
Si 24 is an orthorhombic crystalline Si allotrope.It was first synthesized in 2014. [5] [6] Creating the allotrope involved forming Na4 Si 24, a polycrystalline compound with help from a tantalum capsule, high temperature, and a 1,500 ton multi-anvil press that gradually reached a pressure of 10 gigapascals (1,500,000 psi).
Atomic oxygen, denoted O or O 1, is very reactive, as the individual atoms of oxygen tend to quickly bond with nearby molecules.Its lowest-energy electronic state is a spin triplet, designated by the term symbol 3 P.