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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.
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.
Isomers do not necessarily share similar chemical or physical properties. Two main forms of isomerism are structural (or constitutional) isomerism, in which bonds between the atoms differ; and stereoisomerism (or spatial isomerism), in which the bonds are the same but the relative positions of the atoms differ. Isomeric relationships form a ...
A historic phase diagram of sulfur. A phase diagram from 1975, presenting data through 1970. The ordinate is pressure in kilobars (kbar). and the abscissa is temperature in kelvins (K). (The temperatures 200, 400, 600, and 800 K correspond to the approximate temperatures of −73, 127, 327, and 527 °C, respectively.)
Structural equivalences between atoms of a parent molecule reduce the number of positional isomers that can be obtained by replacing those atoms for a different element or group. Thus, for example, the structural equivalence between the six hydrogens of ethane C 2 H 6 means that there is just one structural isomer of ethanol C 2 H 5 OH, not 6.
The reasons for the complicated phase diagram are not entirely understood; recent research has focused on constructing accurate computer models of the phase transitions. The α phase has a low-symmetry monoclinic structure, [ 7 ] hence its poor conductivity, brittleness, strength and compressibility.
Stereochemistry, a subdiscipline of chemistry, studies the spatial arrangement of atoms that form the structure of molecules and their manipulation. [1] The study of stereochemistry focuses on the relationships between stereoisomers, which are defined as having the same molecular formula and sequence of bonded atoms (constitution) but differing in the geometric positioning of the atoms in space.
These reports also detail the isolation of a key intermediate, pentaarsaferrocene ([Cp R Fe(μ 5-As 5)]). [18] This intermediate, isolobal to ferrocene, replaces one of the cyclopentadienyl ligands with a cyclic As 5 ligand that features As-As bond lengths of 2.312 Å (in line with delocalized As-As double bonds). This "sandwich-forming ...