Phosphorus, black white

Phosphorous acid, 372 Phosphorus black, 365 boiling point, 374 chemistry of, 368 compounds, 102 heat of vaporization, 374 ionization energy, 268 melting point, 374 occurrence, 373 oxyacids, 371, 372 preparation, 374, 376 properties, 101 structure, 366 white, 120, 365, 366, 369 Photon, 254... 

Reactivity of white phosphorus is much greater than red or black phosphorus. Black phosphorus is the least reactive of all phosphorus allotropes. 

Ores of phosphorus apatite, hydroxy-apatite, iricalcium phosphate (phosphate rock). White phosphorus, red phosphorus, black phosphorus. High polymers and their properties. Manufacture and uses of phosphorus. Ordinary matches, safety matches. 

Depending upon the nature of interatomic bonds established during its formation, solid elemental phosphorus could occur in three allotropic forms black, white (yellow), or red. Other forms of phosphorus are... 

Two more stable phosphorus allotropes are red and black phosphorus. Small amounts of these are are also produced for special purposes from the white phosphorus product of the electric arc furnace. Red phosphorus is obtained by heating white phosphorus at 400°C for several hours, which yields a complex polymeric material, more dense (2.20 g/cm ) and considerably more stable than the white variety. Red phosphorus is not only stable in air, but far less toxic than white phosphorus. Black phosphorus is more dense again (2.25-2.69g/cm ), and has a different more complex structure. It is obtained by heating the white variety at 220 to 370°C for 8 days plus requires either a pressure exceeding 10 kg/cm or a seed crystal of black phosphorus. This product has a structure resembling graphite, is a good electrical conductor, and can be lit with a match only with difficulty [10] (Table 10.3). 

Phosphorus comes in three colors white, red, and black. White phosphorus is a waxy solid that glows in the dark. It is used to make useful products, such as fertilizers, weed killers, and cleaning products. Sulfur is a soft yellow solid. In the past, it was used to fumigate houses. It can kill plant fungi. Today, sulfur is in all kinds of chemicals. It is used to harden rubber. 

In the introduction we defined exotic as beautiful, exceptional, weird, paradoxical, and counterintuitive. We also indicated that such species could represent fragile and rare as well as simple and well-characterized classic inorganic compounds. In this section we will look at two of the simplest inorganic classes of compounds polyphosphorus and polynitrogen species. We will dwell on the following elementary question Why is it that polyphosphorus allotropes of the element are well known (white phosphorus black phosphorus in its orthorhombic, rhom-bohedral, and cubic forms red, amorphous phosphorus). 

The remaining forms of elemental phosphoms, namely black and red phosphorus, are insoluble polymers that are much less reactive than white phosphorus. Black orthorhombic phosphorus is the most thermodynamically stable form of this element and can be obtained by heating white phosphorus under pressure. Red phosphorus, in contrast to the black allotrope, is not crystalline but amor-... 

Phosphorus exists in three forms, white, red and black (violet). The white modification is a waxy solid, very toxic and inflammable. Heated to 300-400°C without contact with air, white is transformed to the non-toxic red phosphorus. If white or red phosphorus is heated to 200°C at a pressure of 12 000 bar (1200 MPa), black phosphorus is formed. Even at low pressure it can however be obtained if red or white is heated at 350°C together with bismuth or mercury. Once formed black phosphorus is stable from low temperatures up to about 400°C. White phosphorus is prepared commercially by heating calcium phosphate with quartz and coke in an electric furnace. Most of the phosphorus produced is converted to phosphoric acid for use in making fertilizer. The element is important in plant and animal physiology and is a constituent of all animal bones, in the form of calcium phosphate. 

A third allotrope of phosphorus is black phosphorus. Black phosphorus is obtained by heating white phosphorus under pressure. This form of phosphorus is the most thermodynamically stable form, and therefore the least reactive. Black phosphorus has a layered structure similar to that of graphite. 

Black phosphorus is formed when white phosphorus is heated under very high pressure (12 000 atmospheres). Black phosphorus has a well-established corrugated sheet structure with each phos phorus atom bonded to three neighbours. The bonding lorces between layers are weak and give rise to flaky crystals which conduct electricity, properties similar to those ol graphite, it is less reactive than either white or red phosphorus. 

White phosphorus is very reactive. It has an appreciable vapour pressure at room temperature and inflames in dry air at about 320 K or at even lower temperatures if finely divided. In air at room temperature it emits a faint green light called phosphorescence the reaction occurring is a complex oxidation process, but this happens only at certain partial pressures of oxygen. It is necessary, therefore, to store white phosphorus under water, unlike the less reactive red and black allotropes which do not react with air at room temperature. Both red and black phosphorus burn to form oxides when heated in air, the red form igniting at temperatures exceeding 600 K,... 

Phosphorus exists in four or more allotropic forms white (or yellow), red, and black (or violet). Ordinary phosphorus is a waxy white solid when pure it is colorless and transparent. White phosphorus has two modifications alpha and beta with a transition temperature at -3.8oC. 

Arsenic modifications with the structures of white and black phosphorus have been described. However, only gray (metallic, rhombohedral) a-arsenic is stable. It consists of layers of six-membered rings in the chair conformation that are connected with each other in the same way as in /ran.v-dccalin (Fig. 11.7). In the layer the atoms are situated alternately in an upper and a lower plane. The layers are stacked in a staggered manner such that over and under the center of every ring there is an As atom in an adjacent layer. In this way every As atom is in contact with three more atoms in addition to the three atoms to which it is bonded within the layer it has a distorted octahedral 3 + 3 coordination. The As-As bond length in the layer is 252 pm the distance between adjacent atoms of different layers is 312 pm and thus is considerably shorter than the van der Waals distance (370 pm). 

The only element that was discovered in body fluids (urine). This is plausible, as P plays a main role in all life processes. It is one of the five elements that make up DNA (besides C, H, N, and 0 evolution did not require anything else to code all life). The P-O-P bond, phosphoric acid anhydride, is the universal energy currency in cells. The skeletons of mammals consists of Ca phosphate (hydroxylapatite). The element is encountered in several allotropic modifications white phosphorus (soft, pyrophoric P4, very toxic), red phosphorus (nontoxic, used to make the striking surface of matchboxes), black phosphorus (formed under high pressures). Phosphates are indispensable as fertilizer, but less desirable in washing agents as the waste water is too concentrated with this substance (eutrophication). It has a rich chemistry, is the basis for powerful insecticides, but also for warfare agents. A versatile element. 

Several allotropic forms of phosphorus are known, the most common of which are the white, red, and black forms. Heating the white form at 400 °C for several hours produces red phosphorus, which is known to include several forms. A red form that is amorphous can be prepared by subjecting white phosphorus to ultraviolet radiation. In the thermal process, several substances (I2, S8, and Na) are known to catalyze the conversion of phosphorus to other forms. Black phosphorus consists of four identifiable forms that result when white phosphorus is subjected to heat and pressure. Phosphorus is used in large quantities in the production of phosphoric acid and other chemicals. White phosphorus has been used extensively in making incendiary devices, and red phosphorus is used in making matches. 

Black phosphorus may be either amorphous or crystalline. It exhibits quite low reactivity, both with oxygen and other reagents, compared to white or red phosphorus, and is stable in air. Because it has a puckered shape, the phosphorus remains tricoordinated in black phosphorus and crystallizes in sheets in a way similar to the behavior of graphite. Black phosphorus is generated from white phosphorus either by heating under pressure or in the presence of mercury. It is of relatively little value for the synthesis of organophosphorus compounds. 

Although black phosphorus is generally inert, red phosphorus and particularly white phosphorus are capable of undergoing reactions to generate organophosphorus compounds. Several different sets of conditions may be used to form C-P bonds from elemental phosphorus. These will be discussed in the following sections. 

There are three main forms of phosphorus, white (soft, waxy solid at room temperature, highly reactive, toxic), red and black. 

The white and black phosphorus structures have been observed also in metastable arsenic modifications. 

Although phosphorus is in group 15 with some other metalloids, it is usually classed as a nonmetal since it resembles nitrogen somewhat, the element above it in group 15. Both are essential to the biochemical field as vital elements to support life. Phosphorus has 10 known allotropic forms. This is an unusually high number for any element. A system of categorizing the allotropes by three colors has made it easier to keep track of them. These three colors are white, red, and black phosphorus. 

Black phosphorus also starts with heating white phosphorus. The difference is that the white phosphorus is heated in the presence of a mercury catalyst and a small amount of already-formed black phosphorus. Its density is 2.4 g/cm. ... 

Black phosphorus is the only one of the three that will conduct electricity white and red are poor conductors. Black phosphorus has no significant commercial uses. 

The cyclic (Dsh) Ps anion, which can be generated from white phosphorus by cleaving either with sodium in diglyme or LiFl2P in THF, forms stable Fe (77 -C5H5)(77 -P5) there is some evidence for the generation of unstable black Fe (P5)2 on treatment of FeCl2 with Ps . " ... 

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