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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.
But a paper in 1988 claimed that a better theory was that the structure was the same as that of an allotrope of silicon called Si-III or γ-silicon, the so-called BC8 structure with space group Ia 3 and 8 atoms per primitive unit cell (16 atoms per conventional unit cell).
Iron allotropes, showing the differences in structure. The alpha iron (α-Fe) is a body-centered cubic (BCC) and the gamma iron (γ-Fe) is a face-centered cubic (FCC). 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).
The lattice structure of violet phosphorus has been obtained by single-crystal x-ray diffraction to be monoclinic with space group of P2/n (13) (a = 9.210, b = 9.128, c = 21.893 Å, β = 97.776°, CSD-1935087). The optical band gap of the violet phosphorus was measured by diffuse reflectance spectroscopy to be around 1.7 eV.
There are several known allotropes of oxygen. The most familiar is molecular oxygen (O2), present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen. Another is the highly reactive ozone (O3). Others are: Atomic oxygen (O1), a free radical. 2), one of two metastable states of molecular oxygen.
Allotropes of boron. 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). In special circumstances, boron can also be synthesized in the form of its α-tetragonal (α-T) and γ-orthorhombic (γ) allotropes.
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 ...
The physical properties of carbon vary widely with the allotropic form. For example, graphite is opaque and black, while diamond is highly transparent. Graphite is soft enough to form a streak on paper (hence its name, from the Greek verb "γράφειν" which means "to write"), while diamond is the hardest naturally occurring material known.