![]() Sodium compounds have been known since ancient times salt ( sodium chloride) has been an important commodity in human activities, as testified by the English word salary, referring to salarium, money paid to Roman soldiers for the purchase of salt. History Petalite, the lithium mineral from which lithium was first isolated Sodium, potassium and lithium are essential elements, having major biological roles as electrolytes, and although the other alkali metals are not essential, they also have various effects on the body, both beneficial and harmful. Lithium finds use as a psychiatric medication and as an anode in lithium batteries. Table salt, or sodium chloride, has been used since antiquity. A common application of the compounds of sodium is the sodium-vapour lamp, which emits light very efficiently. 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. The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr).
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