Alkali, AL kuh ly, in chemistry, refers to six chemical elements that are known as the alkali metals: lithium, sodium, potassium, rubidium, cesium, and francium. These elements make up group 1 of the periodic table. Compounds of alkali metals rank among the most common and most useful of all chemicals. Millions of tons of alkali metal salts are used by industry each year. The salts come from mines and wells. Sodium and potassium salts are raw materials for sodium hydroxide and potassium hydroxide. These alkali metal compounds and others made from them are used in making glass, paper, soap, and textiles; in refining petroleum; and in preparing leather. The word alkali comes from the Arabic word al-qili, meaning plant ashes. Plant ashes were the first source of alkali metal compounds.