![]() ![]() One of the best-known applications of the pure elements is the use of rubidium and caesium in atomic clocks, of which caesium atomic clocks form the basis of the second. Most alkali metals have many different applications. However, ununennium may not be an alkali metal due to relativistic effects, which are predicted to have a large influence on the chemical properties of superheavy elements even if it does turn out to be an alkali metal, it is predicted to have some differences in physical and chemical properties from its lighter homologues. Experiments have been conducted to attempt the synthesis of element 119, which is likely to be the next member of the group none were successful. All the alkali metals react with water, with the heavier alkali metals reacting more vigorously than the lighter ones.Īll 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 side branches of the natural decay chains. Caesium, the fifth alkali metal, is the most reactive of all the metals. Because of their high reactivity, they must be stored under oil to prevent reaction with air, and are found naturally only in salts and never as the free elements. They can all be cut easily with a knife due to their softness, exposing a shiny surface that tarnishes rapidly in air due to oxidation by atmospheric moisture and oxygen (and in the case of lithium, nitrogen). The alkali metals are all shiny, soft, highly reactive metals at standard temperature and pressure and readily lose their outermost electron to form cations with charge +1. This family of elements is also known as the lithium family after its leading element. Indeed, the alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterised homologous behaviour. All alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having very similar characteristic properties. Together with hydrogen they constitute group 1, which lies in the s-block of the periodic table. ^ This element has not been discovered/synthesized.The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr)., indicates the mass number of the longest-lived isotope of the element or characteristic isotopic composition. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj The element does not have any stable nuclides, and a value in brackets, e.g.^ The atomic weight of commercial Lithium can vary between 6.939 and 6.996-analysis of the specific material is necessary to find a more accurate value.^ a b c d e f g h i j k l m n o The isotopic composition varies in terrestrial material such that a more precise atomic weight can not be given.^ a b c d e f g h The isotopic composition of the element can vary in commercial materials, which can cause the atomic weight to deviate significantly from the given value. ![]() ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am The isotopic composition of this element varies in some geological specimens, and the variation may exceed the uncertainty stated in the table. ![]() Element categories in the periodic table Metals ![]()
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