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Europium is a chemical element; it has symbol Eu and atomic number 63. It is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. Europium is the most chemically reactive, least dense, and softest of the lanthanides. It is soft enough to be cut with a knife.
Europium compounds are compounds formed by the lanthanide metal europium (Eu). In these compounds, europium generally exhibits the +3 oxidation state, such as EuCl 3, Eu(NO 3) 3 and Eu(CH 3 COO) 3. Compounds with europium in the +2 oxidation state are also known. The +2 ion of europium is the most stable divalent ion of lanthanide metals in ...
In the cartography of the United States, the American polyconic projection is a map projection used for maps of the United States and its regions beginning early in the 19th century. It belongs to the polyconic projection class , which consists of map projections whose parallels are non- concentric circular arcs except for the equator , which ...
between North America and South America (dividing the Americas): at some point on the Isthmus of Panama, with the most common demarcation in atlases and other sources following the Darién Mountains watershed along the Colombia–Panama border where the isthmus meets the South American continent (see Darién Gap).
Mercator's original map is truncated at 80°N and 66°S with the result that European countries were moved toward the centre of the map. The aspect ratio of his map is 198 / 120 = 1.65. Even more extreme truncations have been used: a Finnish school atlas was truncated at approximately 76°N and 56°S, an aspect ratio of 1.97.
Rare-earth element abundances of basalts, of both terrestrial and lunar origins [1]. The europium anomaly is the phenomenon whereby the europium (Eu) concentration in a mineral is either enriched or depleted relative to some standard, commonly a chondrite or mid-ocean ridge basalt (MORB).
However, without a clarifying context, singular America in English commonly refers to the United States of America. [2] Historically, in the English-speaking world, the term America could refer to a single continent until the 1950s (as in Van Loon's Geography of 1937): According to historians Kären Wigen and Martin W. Lewis, [3]
A New Map of Europe According to the Newest Observations (1721) by Hermann Moll draws the eastern boundary of Europe along the Don River flowing south-west and the Tobol, Irtysh and Ob rivers flowing north. 1916 political map of Europe showing most of Moll's waterways replaced by von Strahlenberg's Ural Mountains and Freshfield's Caucasus crest ...