cesium — /see zee euhm/, n. a rare, highly reactive, soft, metallic element of the alkali metal group, used chiefly in photoelectric cells. Symbol: Cs; at. wt.: 132.905; at. no.: 55; sp. gr.: 1.9 at 20°C; melts at 28.5°C. Also, caesium. [1930 35; < NL,… … Universalium
Caesium — xenon ← caesium → barium Rb ↑ Cs ↓ Fr … Wikipedia
Accident nucléaire de Fukushima — 37° 25′ 17″ N 141° 01′ 57″ E / 37.42138889, 141.0325 … Wikipédia en Français
chemical compound — Introduction any substance composed of identical molecules consisting of atoms (atom) of two or more chemical elements (chemical element). All the matter in the universe is composed of the atoms of more than 100 different chemical elements … Universalium
POLLUTION — Bien que d’usage banal à l’heure actuelle, le terme de pollution recouvre des acceptions fort diverses et qualifie une multitude d’actions qui dégradent d’une façon ou d’une autre le milieu naturel. Certes, le vocable désigne sans ambiguïté les… … Encyclopédie Universelle
environment — environmental, adj. environmentally, adv. /en vuy reuhn meuhnt, vuy euhrn /, n. 1. the aggregate of surrounding things, conditions, or influences; surroundings; milieu. 2. Ecol. the air, water, minerals, organisms, and all other external factors… … Universalium
HORLOGES ATOMIQUES — Les horloges atomiques utilisent des transitions entre des niveaux d’énergie bien définis de certains atomes. Leur développement, depuis les années 1950, fait appel à la conjonction de plusieurs disciplines. Il résulte, d’une part, des… … Encyclopédie Universelle
radiation — radiational, adj. /ray dee ay sheuhn/, n. 1. Physics. a. the process in which energy is emitted as particles or waves. b. the complete process in which energy is emitted by one body, transmitted through an intervening medium or space, and… … Universalium
poison — poisoner, n. poisonless, adj. poisonlessness, n. /poy zeuhn/, n. 1. a substance with an inherent property that tends to destroy life or impair health. 2. something harmful or pernicious, as to happiness or well being: the poison of slander. 3.… … Universalium
2011 Tōhoku earthquake and tsunami — 2011 Miyagi earthquake redirects here. For the aftershock that occurred on 7 April, see April 2011 Miyagi earthquake. 2011 Tōhoku earthquake and tsunami 東日本大震災 An aerial view of damage in the Tōhoku region with black smoke coming from the Nippon… … Wikipedia
alkali metal — Chem. any of the group of univalent metals including potassium, sodium, lithium, rubidium, cesium, and francium, whose hydroxides are alkalis. [1880 85] * * * Any of the six chemical elements in the leftmost group of the periodic table (lithium,… … Universalium