phosphore
- Domaine
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- chimiechimie minérale
- Dernière mise à jour
Définition :
Élément chimique non-métallique et pentavalent qui se présente sous deux formes : le phosphore blanc ou jaune, solide, semi-transparent, toxique et hautement inflammable et le phosphore rouge ou amorphe, poudre brun-rouge non toxique et non inflammable. Numéro atomique 15; masse atomique 30,97; ion 5+ de rayon 0,35 angstrom; densité 1,85; clarke 1050 à 1180 g/t, selon les auteurs.
Notes :
Il est en général associé à l'oxygène pour former le radical des phosphates.
En électronique, on l'utilise pour le dopage des semiconducteurs. En incorporant du phosphore au silicium, par exemple, on obtient un semiconducteur extrinsèque de type n, c'est-à-dire que l'on fait apparaître dans le silicium des porteurs de charges libres qui sont des électrons.
En médecine, on l'emploie uniquement sous la forme de l'acide phosphorique et de ses sels toxiques. Il entraîne la dégénérescence graisseuse des organes et surtout du foie.
Termes privilégiés :
- phosphore n. m.
- P
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[phosphore] Du grec phôs, lumière, et phoros, qui porte.
[P] Anciennement Ph.
Traductions
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anglais
Auteur : Office québécois de la langue française,Notes :
In some respects, phosphorus is not form, designated by their color-two white forms differing in their crystal structure, a red-violet, and a black allotrope, the last two being either amorphous or crystalline. The white allotropes are pyrophoric, but the black does not ignite easily. Phosphorus also resembles carbon in its tendency for covalent bonds, though it does not bond to itself as readily as carbon. It occurs widely in rock structures, which are its principal source, as well as in the guano deposits found on islands frequented by sea birds.
Phosphorous vapour condenses at 280°C to liquid white phosphorus, which solidifies at 44°C to solid white phosphorus, which is soft, waxy, colourless, soluble in carbon disulphide and benzene.
It is insoluble in water.
The name is due to its property of emitting absorbed radiation in the dark (slow oxydation) at room temperature; it may be either fluorescent or phosphorescent depending on whether or not it emits light after the exciting source has been removed. It is made by reduction of the calcium phosphate in phosphate rock in an electric furnace with silica and carbon. Phosphorus is an essential nutrient for plants and animals and has complex metabolic functions (as adenosine triphosphate) in addition to its hardening effect on bones and teeth (as hydroxyapatite). In elemental form it is highly toxic, causes severe burns, and some of its organic compounds (nerve gases and insecticides of the parathion type) are lethally poisonous. The chief uses of elemental phosphorus are in the manufacture of numerous compounds (phosphoric acid, combinations with halogens, sulfur, etc., and organophosphorus compounds), as a semiconductor and catalyst, in pyrotechnic devices, and in deoxidizing metals.Termes :
- phosphorus
- P