Alkali+metal

=**Alkali Metals:**=

The **alkali metals** are a group of chemical elements in the periodic table with very similar properties: they are all shiny, soft, silvery, highly reactive metals at standard temperature and pressure and readily lose their outermost electron to form cations with charge +1. 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. In the modern IUPAC nomenclature, the alkali metals comprise the **group 1 elements**, excluding hydrogen (H), which is nominally a group 1 element   but not normally considered to be an alkali metal   as it rarely exhibits behaviour comparable to that of the alkali metals. The alkali metals are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). This group lies in the s-block of the periodic table as all alkali metals have their outermost electron in an s-orbital. The alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterized homologous behaviour. All the discovered alkali metals occur in nature. Experiments have been conducted to attempt the synthesis of ununennium (Uue), which is likely to be the next member of the group, but they have all met with failure. 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. Most alkali metals have many different applications. Two of the most well-known applications of the pure elements are rubidium and caesium atomic clocks, of which caesium atomic clocks are the most accurate representation of time known as of 2012. A common application of the compounds of sodium is the sodium vapour lamp, which emits very efficient light. Table salt, or sodium chloride, has been used since antiquity.