Search results
Results from the WOW.Com Content Network
Black phosphorus is the thermodynamically stable form of phosphorus at room temperature and pressure, with a heat of formation of −39.3 kJ/mol (relative to white phosphorus which is defined as the standard state). [1] It was first synthesized by heating white phosphorus under high pressures (12,000 atmospheres) in 1914.
Therefore, this form is sometimes known as "Hittorf's phosphorus" (or violet or α-metallic phosphorus). [19] Black phosphorus is the least reactive allotrope and the thermodynamically stable form below 550 °C (1,022 °F). It is also known as β-metallic phosphorus and has a structure somewhat resembling that of graphite.
White phosphorus is also the most common, industrially important, and easily reproducible allotrope, and for these reasons is regarded as the standard state of phosphorus. The most stable form is the black allotrope, which is a metallic looking, brittle and relatively non-reactive semiconductor (unlike the white allotrope, which has a white or ...
Phosphorus, as black phosphorus. Phosphorus in its most thermodynamically stable black form, is a lustrous and comparatively unreactive solid with a density of 2.69 g/cm 3, and is soft (MH 2.0) and has a flaky comportment. It sublimes at 620 °C. Black phosphorus has an orthorhombic crystalline structure (CN 3).
The darker more stable isotope region departs from the line of protons (Z) = neutrons (N), as the element number Z becomes larger. This is a list of chemical elements by the stability of their isotopes. Of the first 82 elements in the periodic table, 80 have isotopes considered to be stable. [1] Overall, there are 251 known stable isotopes in ...
Although phosphorus (15 P) has 22 isotopes from 26 P to 47 P, only 31 P is stable; as such, phosphorus is considered a monoisotopic element. The longest-lived radioactive isotopes are 33 P with a half-life of 25.34 days and 32 P with a half-life of 14.268 days. [3] [4] All others have half-lives of under 2.5 minutes, most under a second.
It is a major industrial chemical, being a component of many fertilizers. The compound is an acid. Removal of all three H + ions gives the phosphate ion PO 3− 4. Removal of one or two protons gives dihydrogen phosphate ion H 2 PO − 4, and the hydrogen phosphate ion HPO 2− 4, respectively. Phosphoric acid forms esters, called organophosphates.
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.