Helium He"li*um (h[=e]"l[i^]*[u^]m), n. [NL., fr. Gr. "h`lios the sun.] (Chem.) An inert, monoatomic, gaseous element occurring in the atmosphere of the sun and stars, and in small quantities in the earth's atmosphere, in several minerals and in certain mineral waters. It is obtained from natural gas in industrial quantities. Symbol, He; atomic number 2; at. wt., 4.0026 (C=12.011). Helium was first detected spectroscopically in the sun by Lockyer in 1868; it was first prepared by Ramsay in 1895. Helium has a density of 1.98 compared with hydrogen, and is more difficult to liquefy than the latter. Chemically, it is an inert noble gas, belonging to the argon group, and cannot be made to form compounds. The helium nucleus is the charged particle which constitutes alpha rays, and helium is therefore formed as a decomposition product of certain radioactive substances such as radium. The normal helium nucleus has two protons and two neutrons, but an isotope with only one neutron is also observed in atmospheric helium at an abundance of 0.013 %. Liquid helium has a boiling point of -268.9[deg] C at atmospheric pressure, and is used for maintaining very low temperatures, both in laboratory experimentation and in commercial applications to maintain superconductivity in low-temperature superconducting devices. Gaseous helium at normal temperatures is used for buoyancy in blimps, dirigibles, and high-altitude balloons, and also for amusement in party balloons. [Webster 1913 Suppl. +PJC]

The Collaborative International Dictionary of English. 2000.

Look at other dictionaries:

  • Helium — Hélium Traduction à relire Helium → …   Wikipédia en Français

  • hélium — [ eljɔm ] n. m. • 1868; lat. sc., du gr. hêlios « soleil » ♦ Chim., phys. Élément chimique (He; no at. 2; m. at. 4), gaz rare très léger, ininflammable. L hélium, rare dans l atmosphère, est abondant dans la chromosphère et les étoiles. L hélium… …   Encyclopédie Universelle

  • Helium — Sn (ein farbloses Edelgas) erw. fach. (19. Jh.) Neoklassische Bildung. Neubildung englischer Naturwissenschaftler zu gr. hḗlios m. Sonne . So benannt, weil die Spektrallinien mit denen eines auf der Sonne nachgewiesenen Elements identisch sind.… …   Etymologisches Wörterbuch der deutschen sprache

  • HELIUM — ostium Rheni, quod et Occ. et Mosae ostium, erat iuxta Helium castr. in parte Austr. Bataviae, ubi urbs Brilla est. Nunc die Maes incolis, Ortel. Secundum Voss. Batavis Hiel unde; vicus Wiidhiel, ubi latius Helus, seu Hilus fluit: item Bree hiel …   Hofmann J. Lexicon universale

  • Helium — Helium: Der Name des Edelgases wurde im 19. Jh. aus gleichbed. engl. helium entlehnt, einer gelehrten Bildung von J. N. von Lockyer (1836–1920) und E. Frankland (1825–1899) zu griech. hē̓lios »Sonne«, das urverwandt ist mit lat. sol und nhd. ↑… …   Das Herkunftswörterbuch

  • Helĭum — Helĭum, gasförmiger Körper, findet sich in sehr großer Menge auf der Sonne und den weißen Fixsternen sowie in dem Meteoriten von Augusta County, auf der Erde in Euxenit, Äschynit, Cleveīt, Bröggerit, Uraninit, Yttrotantalit, Fergusonit, Samarskit …   Meyers Großes Konversations-Lexikon

  • Helium — Helĭum (chem. Zeichen He), gasförmiges Element, von Lockyer 1868 im Spektrum der Sonne und weißen Fixsterne entdeckt, 1895 von Ramsay in den Gasen seltener Mineralien (Samarskit, Uranit, Cleveït), auch in Mineralquellen und spurenweise in der… …   Kleines Konversations-Lexikon

  • helium — HÉLIUM s.n. v. heliu. Trimis de LauraGellner, 13.09.2007. Sursa: DN …   Dicționar Român

  • helium — Symbol: He Atomic number: 2 Atomic weight: 4.0026 Colourless, odourless gaseous nonmetallic element. Belongs to group 18 of the periodic table. Lowest boiling point of all elements and can only be solidified under pressure. Chemically inert, no… …   Elements of periodic system

  • helium — 1868, coined from Gk. helios sun (see SOL (Cf. sol)), because the element was detected in the solar spectrum during the eclipse of Aug. 18, 1868, by English astronomer Sir Joseph N. Lockyer (1836 1920) and English chemist Sir Edward Frankland… …   Etymology dictionary

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