Search results
Results from the WOW.Com Content Network
Caesium (IUPAC spelling; [9] also spelled cesium in American English) is a chemical element; it has symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of 28.5 °C (83.3 °F; 301.6 K), which makes it one of only five elemental metals that are liquid at or near room temperature.
To give provisional names to his predicted elements, Dmitri Mendeleev used the prefixes eka- / ˈ iː k ə-/, [note 1] dvi- or dwi-, and tri-, from the Sanskrit names of digits 1, 2, and 3, [3] depending upon whether the predicted element was one, two, or three places down from the known element of the same group in his table.
Note: René Haüy discovered that emeralds and beryls crystals are geometrically identical. He asked Vauquelin for a chemical analysis, and so Vauquelin found a new "earth" (beryllium oxide). Carl Wilhelm Scheele (1742 –1786), discovery of oxygen with Priestley; identification of molybdenum, tungsten, barium, hydrogen, and chlorine.
Perey discovered it as a decay product of 227 Ac. [177] Francium was the last element to be discovered in nature, rather than synthesized in the lab, although four of the "synthetic" elements that were discovered later (plutonium, neptunium, astatine, and promethium) were eventually found in trace amounts in nature as well. [178]
Caesium (Cs) 55 caesius: Latin "blue-gray" [43] or "sky blue" descriptive (colour) From Latin caesius, which means "sky blue". Its identification was based upon the bright-blue lines in its spectrum, and it was the first element discovered by spectrum analysis. Barium (Ba) 56 βαρύς (barys) Greek via Neo-Latin "heavy" βαρύς (barys ...
Francium was discovered by Marguerite Perey [4] in France (from which the element takes its name) on January 7, 1939. [5] Before its discovery, francium was referred to as eka-caesium or ekacaesium because of its conjectured existence below caesium in the periodic table. It was the last element first discovered in nature, rather than by synthesis.
Around 420 BC, Empedocles stated that all matter is made up of four elemental substances: earth, fire, air and water. The early theory of atomism can be traced back to ancient Greece . Greek atomism was made popular by the Greek philosopher Democritus , who declared that matter is composed of indivisible and indestructible particles called ...
All of the discovered alkali metals occur in nature as their compounds: in order of abundance, sodium is the most abundant, followed by potassium, lithium, rubidium, caesium, and finally francium, which is very rare due to its extremely high radioactivity; francium occurs only in minute traces in nature as an intermediate step in some obscure ...