Earlier version first published in New English Dictionary, 1888. Second edition, 1989 online version June 2012 accessed 07 September 2012. "History of the recommended atomic-weight values from 1882 to 1997: a comparison of differences from current values to the estimated uncertainties of earlier values" (PDF). Washington, D.C.: American Chemical Society. The ACS Style Guide: Effective Communication of Scientific Information (3rd ed.). Nomenclature o Inorganic Chemistry (IUPAC Recommendations 2005). ↑ Internaitional Union o Pure an Applee'd Chemistry (2005).↑ "NIST Radionuclide Half-Life Measurements".Handbook of Chemistry and Physics (PDF) (87th ed.). ↑ "Magnetic susceptibility of the elements and inorganic compounds"."Atomic weights of the elements 2013 (IUPAC Technical Report)". The alkali metals are so called because reaction with water forms alkalies (i.e., strong bases capable of neutralizing acids ). ↑ Alang wi rubidium (39 ☌ ), francium (estimatit at 27 ☌ ), mercur (−39 ☌ ), an gallium (30 ☌ ) bromine is an aa liquid at ruim temperatur (meltin at −7.2 ☌, 19 ☏) but it is a halogen, nae a metal. alkali metal, any of the six chemical elements that make up Group 1 (Ia) of the periodic table namely, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).Hence, an alternative orthography is cæsium. The element wis named efter the Latin word cæsius, meanin "bluish gray". The American Chemical Society (ACS) haes uised the spellin cesium syne 1921, follaein Webster's New International Dictionary. ↑ Caesium is the spellin recommendit bi the Internaitional Union o Pure an Applee'd Chemistry (IUPAC). Altho the element is anly mildly toxic, it is a hazardous material as a metal an its radioisotopes present a heich heal risk if released intae the environment. The radioactive isotope caesium-137 haes a hauf-life o aboot 30 year an is uised in medical applications, industrial gauges, an hydrology. It haes a range o applications in the production o electricity, in electronics, an in chemistry. Syne the 1990s, the lairgest application o the element haes been as caesium formate for drilling fluids. Syne then, caesium haes been widely uised in atomic clocks. In 1967, a specific frequency frae the emission spectrum o caesium-133 wis chosen tae be uised in the definition o the seicont bi the Internaitional Seestem o Units. The first smaa-scale applications for caesium wur as a " getter" in vacuum tubes an in photoelectric cells. Twa German chemists, Robert Bunsen an Gustav Kirchhoff, discovered caesium in 1860 bi the newly developed method o flame spectroscopy. Caesium is mined maistly frae pollucite, while the radioisotopes, especially caesium-137, a fission product, are extractit frae waste produced bi nuclear reactors. It is the least electronegative element havin a stable isotope, caesium-133. The metal is extremely reactive an pyrophoric, reactin wi watter even at −116 ☌ (−177 ☏). Compounds like this consist of a giant (endlessly repeating) lattice of ions. Atomic number: 55 Atomic weight (mass): 132.9054 g.mol-1 Group number: 1 (Alkali metals) Period: 6 Color: Silvery-golden alkali metal Physical state: Liquid at or near room temperature Half-life: From 500(100) s to 2.3 million years Electronegativity according to Pauling: 0.79 Density: 1.9 g.cm-3 at 20C Melting point: 28.5 C (83. The structure of a typical ionic solid - sodium chloride Sodium chloride is taken as a typical ionic compound. Caesium is an alkali metal an haes pheesical an chemical properties seemilar tae those o rubidium an potassium. It also explains why cesium chloride has a different structure from sodium chloride even though sodium and cesium are both in Group 1 of the Periodic Table. It is a saft, sillery-gowd alkali metal wi a meltin pynt o 28 ☌ (82 ☏), which maks it ane o anly five elemental metals that are liquid at or near ruim temperatur.
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