alkali
The elements of group 1 are called the alkali metals. Alkali from the Arabic al-qili, meaning ashes of the saltwort plant from salt marshes was a general term for substances derived from wood ashes, all of which possessed a bitter taste and were able to neutralize acids. Although oxides of both group 1 and group 2 elements were obtained from wood ashes, the alkali metals had lower melting points. Potassium and sodium were first isolated in 1807 by the British chemist Sir Humphry Davy 17781829 by passing an electrical current through molten samples of potash K2CO3 and soda ash Na2CO3 . The potassium burst into flames as soon as it was produced because it reacts readily with oxygen at the higher temperature. However, the group 1 elements, like the group 2 elements, become less reactive with air or water as their atomic number decreases. The heaviest element francium was not discovered until 1939. It is so radioactive that studying its chemistry is very difficult. The alkali metals have ns1 valence electron configurations and the lowest electronegativity of any group; hence they are often referred to as being electropositiveelements. As a result, they have a strong tendency to lose their single valence electron to form compounds in the +1 oxidation state, producing the EX monohalides and the E 2O oxides. Because they are so reactive, pure group 1 elements are powerful reducing agents that are used in lithium batteries and cardiac pacemakers. Sodium salts such as common table salt NaCl , baking soda NaHCO3 , soda ash Na2CO3 ,.