Once obtained as pure metal, the alkali metals then can be used as sources of reducing power in other chemical reactions. Sodium is the usual choice in industry because of its ready availability. All the alkali metals must be kept away from air and water because of their strong tendency to return to the +1 oxidation state. Thus when stored they must be immersed in kerosene or some other organic liquid. Cesium and rubidium have few uses, the most important being as electron-releasing metal surfaces in photoelectric devices.

Sodium and potassium ions are important in living organisms. Their contribution to the composition of a human is shown in the periodic table on the front end papers. and help to keep the proper ionic balance inside and outside cells, so that the cells do not shrink or swell as their surroundings change in salt concentration. They also are involved in triggering nerve impulses down an axon of a neural cell, and hence are critical to the communication system of the body.

The main positive ion inside cells is , and predominates in the blood and body fluids outside the cells. The ionic composition of these body fluids is close to that of sea water diluted with three volumes of pure water. This is not surprising, in view of the evolution of life in the oceans. In a sense, our cells have found a way of carrying around a bit of ocean with them long after our ancestors left it physically.

The main alkali metal ion in plants is rather than . A traditional source of potassium hydroxide, KOH, has been the leaching, or extraction, of wood ashes with water. The name "potassium" for the metal comes from the old English term "pot ash" or "cooking ashes." "Alkali" has the same meaning in Arabic: "al Kali" means "the ashes." The Arabic word ultimately leads back to the Greek word for burning, which drifted off in a different direction via the Latin "caleo," to reach us again in "calorie" and "cauldron."