Search results
Results from the WOW.Com Content Network
Diamond and graphite are two allotropes of carbon: pure forms of the same element that differ in crystalline structure.. 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.
Phagraphene: Graphene-like allotrope with distorted Dirac cones. Prismane C 8 is a theoretically predicted metastable carbon allotrope comprising an atomic cluster of eight carbon atoms, with the shape of an elongated triangular bipyramid—a six-atom triangular prism with two more atoms above and below its bases. [46]
Black phosphorus has an orthorhombic pleated honeycomb structure and is the least reactive allotrope, a result of its lattice of interlinked six-membered rings where each atom is bonded to three other atoms. [22] [23] In this structure, each phosphorus atom has five outer shell electrons. [24]
In addition to the allotropes, each allotrope often exists in polymorphs (different crystal structures of the same covalently bonded S n molecules) delineated by Greek prefixes (α, β, etc.). [2] Furthermore, because elemental sulfur has been an item of commerce for centuries, its various forms are given traditional names.
Triatomic oxygen (ozone, O 3) is a very reactive allotrope of oxygen that is a pale blue gas at standard temperature and pressure. Liquid and solid O 3 have a deeper blue color than ordinary O 2, and they are unstable and explosive. [5] [6] In its gas phase, ozone is destructive to materials like rubber and fabric and is damaging to lung tissue ...
Plutonium normally has six allotropes and forms a seventh (zeta, ζ) under high temperature and a limited pressure range. [2] [3] [4] These allotropes have very similar energy levels but significantly varying densities and crystal structures.
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.
The latter allotrope is a very hard [n 1] grey material, about ten percent lighter than aluminium and with a melting point (2080 °C) several hundred degrees higher than that of steel. [6] Elemental boron has been found in star dust and meteorites, but does not exist in the high oxygen environment of Earth.