allotropy

allotropy
/euh lo"treuh pee/, n. Chem.
a property of certain elements, as carbon, sulfur, and phosphorus, of existing in two or more distinct forms; allomorphism.
Also, allotropism.
[1840-50; ALLO- + -TROPY]

* * *

      the existence of a chemical element in two or more forms, which may differ in the arrangement of atoms in crystalline solids or in the occurrence of molecules that contain different numbers of atoms. The existence of different crystalline forms of an element is the same phenomenon that in the case of compounds is called polymorphism. Allotropes may be monotropic, in which case one of the forms is the most stable under all conditions, or enantiotropic, in which case different forms are stable under different conditions and undergo reversible transitions from one to another at characteristic temperatures and pressures.

      Elements exhibiting allotropy include tin, carbon, sulfur, phosphorus, and oxygen. Tin and sulfur are enantiotropic: the former exists in a gray form, stable below 13.2° C, and a white form, stable at higher temperatures; sulfur forms rhombic crystals, stable below 95.5° C, and monoclinic crystals, stable between 95.5° C and the melting point (119° C). Carbon, phosphorus, and oxygen are monotropic; graphite is more stable than diamond, red phosphorus is more stable than white, and diatomic oxygen, having the formula O2, is more stable than triatomic oxygen (ozone, O3) under all ordinary conditions.

* * *


Universalium. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • Allotropy — (Gr. allos , other, and tropos , manner) is a behavior exhibited by certain chemical elements: these elements can exist in two or more different forms, known as allotropes of that element. In each different allotrope, the element s atoms are… …   Wikipedia

  • allotropy — allotropy. См. аллотропия. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Allotropy — Allotropy. См. Аллотропия. (Источник: «Металлы и сплавы. Справочник.» Под редакцией Ю.П. Солнцева; НПО Профессионал , НПО Мир и семья ; Санкт Петербург, 2003 г.) …   Словарь металлургических терминов

  • allotropy — [ə lä′trə pē] n. [< Gr allotropos, of or in another manner < allos, other + tropos, way, turn: see TROPE] the property that certain chemical elements and compounds have of existing in two or more different forms, as carbon in the form of… …   English World dictionary

  • Allotropy — Allotropism Al*lot ro*pism, Allotropy Al*lot ro*py, n. [Gr. ? other + direction, way, ? to turn: cf. F. allotropie.] (Chem.) The property of existing in two or more conditions which are distinct in their physical or chemical relations. [1913… …   The Collaborative International Dictionary of English

  • allotropy — the property possessed by certain elements to exist in two or more distinct forms that are chemically identical but have different physical properties. In the case of iron the crystal structure has one form at room temperature and another at high …   Mechanics glossary

  • allotropy — alotropija statusas T sritis chemija apibrėžtis Elemento gebėjimas sudaryti kelias vienines medžiagas. atitikmenys: angl. allotropy rus. аллотропия …   Chemijos terminų aiškinamasis žodynas

  • allotropy — alotropija statusas T sritis fizika atitikmenys: angl. allotropy vok. Allotropie, f rus. аллотропия, f pranc. allotropie, f; énantiotropie, f …   Fizikos terminų žodynas

  • allotropy — allotrope ► NOUN Chemistry ▪ each of two or more different physical forms in which an element can exist (e.g. graphite, charcoal, and diamond as forms of carbon). DERIVATIVES allotropic adjective allotropy noun. ORIGIN from Greek allotropos of… …   English terms dictionary

  • allotropy — noun (plural pies) Date: 1850 the existence of a substance and especially an element in two or more different forms (as of crystals) usually in the same phase • allotropic adjective …   New Collegiate Dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”