![]() It occurs chiefly as a hydrated aluminosilicate mineral known as pollucite, 2Cs 2O 2Al 2O 3 9SiO 2 H 2O, mined in the Bernic Lake region of Manitoba.Ĭesium is the largest naturally occurring element it has an atomic radius of 2.65 Å. Natural cesium consists of a single stable isotope, Cs≡33. It can be identified qualitatively in a flame test from the pale violet light given off by the electronic transitions in the excited metal atoms. Cesium, from the Latin caesius, meaning heavenly blue, was named after the color of the most prominent line in its spectrum ( = 455.5 nm). Kirchhoff in 1860, the year after they invented the spectroscope. = ≧8 ✬).Ĭesium was the first element to be discovered using spectroscopic means by Robert W. Cesium readily alloys with the other alkali metals, and a composition of 41% Cs, 47% K, and 12% Na produces the lowest melting metallic alloy known (m.p. Cesium melts just above room temperature at 28.6 ✬, giving it the second lowest melting point relative to mercury (m.p. Even more remarkable is that the cesium begins to melt as it makes it way around the classroom. ![]() When the undergraduates actually hold the sealed glass vial containing cesium, most are surprised to see a golden reflective material, the only other metal besides gold and copper that is not silvery in color. Cesium reacts with water-phenolphthalein in solution. Uses: Used as a catalyst promoter, as a "getter," in radiation monitoring equipment, and in atomic clocks.īUBBLE, BUBBLE. Cesium reacts explosively with cold water, and reacts with ice at temperatures above ≡16 º C. Occurrence: Primarily obtained from the mineral pollucite.Īppearance: Silvery gold, soft, ductile metal.īehavior: The most electropositive and alkaline element. History: Discovered in 1860 by German chemists Robert Bunsen and Gustav Kirchhoff. The metal is characterized by two bright blue lines in its spectrum. Name: From the Latin caesius, heavenly blue. Note that the alkali-in-water experiment is carried out wearing safety glasses and with a clear plastic blast shield to protect the students. Thus, cesium is the most reactive of the alkali metals. This occurs much more rapidly as one goes down the column of alkali metals, since as size increases the ionization potential decreases. The fireworks are created from the exothermicity of the reaction igniting the hydrogen gas. I then add phenolphthalein to one of the beakers, producing the characteristic pink color of base and explain that the reaction of alkali metal with water forms alkali hydroxide and hydrogen. Although many of the students might like to see the violent explosion that would ensue when cesium hits water, those in the front of the room are especially relieved when I just pass around the sealed cesium vial. Lithium sizzles, sodium sparks, and potassium bursts into flames, so merely holding up a vial of cesium causes quite a stir in the classroom. ![]() W hen I teach introductory inorganic chemistry, one of my favorite experiments is to toss alkali metals into a beaker of water. C&EN: IT'S ELEMENTAL: THE PERIODIC TABLE - CESIUM IT'S ELEMENTAL!ĬESIUM RICHARD KANER ,UNIVERSITY OF CALIFORNIA, LOS ANGELES
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |