Any of a group of soft, white, low-density, low-melting, highly reactive metallic elements, including lithium, sodium, potassium, rubidium, cesium, and francium. Any of the six chemical elements in the leftmost group of the periodic table (lithium, sodium, potassium, rubidium, cesium, and francium). They form alkalies when they combine with other elements. Because their atoms have only one electron in the outermost shell, they are very reactive chemically (they react rapidly, even violently, with water), form numerous compounds, and are never found free in nature
any of the monovalent metals of group I of the periodic table (lithium or sodium or potassium or rubidium or cesium or francium); "the hydroxides of the alkali metals are strongly alkaline
A metal from the first row of the periodic table Sodium (Na), potassium (K) and lithium (Li) are the most common Their salts melt when subjected to high temperatures, and their hydroxides are all soluble and form strong basic corrosives (pH = 14) These metals have characteristic flame colors