oxygen group element — ▪ chemical element Introduction also called chalcogen, any of the five chemical elements making up Group 16 (VIa) of the periodic classification namely, oxygen, sulfur, selenium, tellurium, and polonium. (See Figure >.) A relationship among… … Universalium
Oxygen — This article is about the chemical element and its most stable form, O2 or dioxygen. For other forms of this element, see Allotropes of oxygen. For other uses, see Oxygen (disambiguation). nitrogen ← oxygen → fluorine ↑ O ↓ … Wikipedia
Rings of Saturn — The full set of main rings, imaged as Saturn eclipsed the Sun from the vantage of the Cassini spacecraft on 15 September 2006 (brightness is exaggerated). The pale blue dot at the 10 o clock position, outside the main rings and just inside the G… … Wikipedia
Solid oxygen — is also used colloquially to refer to oxidizers such as perchlorates, chlorates, or iodine pentoxide from which oxygen can be produced. Solid oxygen forms at normal atmospheric pressure at a temperature below 54.36 K (−218.79 °C, −361.82 °F).… … Wikipedia
heterocyclic compound — Any of a class of organic compounds whose molecules contain one or more rings of atoms with at least one atom (the heteroatom) being an element other than carbon, most frequently oxygen, nitrogen, or sulfur. As in regular cyclic hydrocarbons,… … Universalium
Physical Sciences — ▪ 2009 Introduction Scientists discovered a new family of superconducting materials and obtained unique images of individual hydrogen atoms and of a multiple exoplanet system. Europe completed the Large Hadron Collider, and China and India took… … Universalium
Mathematics and Physical Sciences — ▪ 2003 Introduction Mathematics Mathematics in 2002 was marked by two discoveries in number theory. The first may have practical implications; the second satisfied a 150 year old curiosity. Computer scientist Manindra Agrawal of the… … Universalium
industrial polymers, major — Introduction chemical compounds used in the manufacture of synthetic industrial materials. In the commercial production of plastics, elastomers, man made fibres, adhesives, and surface coatings, a tremendous variety of polymers are… … Universalium
tree — treelike, adj. /tree/, n., v., treed, treeing. n. 1. a plant having a permanently woody main stem or trunk, ordinarily growing to a considerable height, and usually developing branches at some distance from the ground. 2. any of various shrubs,… … Universalium
Tree — /tree/, n. Sir Herbert Beerbohm /bear bohm/, (Herbert Beerbohm), 1853 1917, English actor and theater manager; brother of Max Beerbohm. * * * I Woody perennial plant. Most trees have a single self supporting trunk containing woody tissues, and in … Universalium
