series of six chemical elements of group IA (1 in the IUPAC nomenclature) of the periodic table. Are tender when compared to other metals and melt at relatively low temperatures. From the chemical point of view, the alkali metals are strong reducing agents: In order to achieve a stable electronic configuration, for they give in easily the single outer electron belonging to the orbit; react violently with water to form metal hydroxides and releasing hydrogen , which caught fire in the air high reaction temperature. Their high reactivity makes them difficult to find pure nature.
In order of increasing atomic number, they are: lithium, sodium, potassium, rubidium, cesium and francium. This element exists only in radioactive form.
Lithium is the founder of the family of alkali metals. It 's the first solid element, since it follows the hydrogen and helium. It 's a very light metal, because its density is about half that of water. And 'the element with the standard reduction potential more negative. These characteristics are, not surprisingly, the key component of the latest battery technology for electronic devices. In the picture you see it float on the solvent in which it is stored.
Sodium is an element to all known and heard, mainly on mineral water. It too is an alkaline and not many know that apart when dissolved in water, is a soft, silvery, easily cut with a knife. Because of its high reactivity is preserved in oil or Vaseline petroleum ether.
Potassium, also tender and brightly colored metal, is characterized by sodium and lithium ahead of him for even greater responsiveness.
rubidium, retain the same properties as its cousins \u200b\u200balkaline but is distinguished by a very high price, of nearly € 150 per gram!
cesium, which is also very expensive, although not as rubidium, has literally marked our time: In 1967 the Thirteenth General Conference on Weights and Measures defined the second as the duration of 9,192,631,770 periods of radiation corresponding the transition between two hyperfine levels of the ground state of the cesuio 133.
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