Alkali metals are used primarily in sodium vapor lamps, table salt and atomic clocks. Alkali metals have the lowest levels of electronegativity and ionization energy and vary in boiling and melting points. Alkali metals are among the most reactive of all metals, which makes them suitable for specific and limited uses.
Alkali metals include lithium, sodium, potassium, rubidium, cesium and francium. These metals have large atomic radii and generally lose electrons during reactions. They have relatively soft textures, which makes them easy to mold, shape and dissect for various uses.
Potassium is a component of KCl, which is a salt that people who need low-sodium diets may use as an alternative to table salt, NaCl. The element's yellow pigmentation makes potassium useful in making items such as dyes and fireworks. Lithium and rubidium are two additional alkali metals that are useful in the production of fireworks and other pyrotechnics. This is because when lithium salts are burned, an intense red color results, while burning rubidium produces a purple color. Lithium is also useful in making the rechargeable lithium-ion batteries that power many electronic devices. Some other items made with rubidium are laser-cooling devices, photocells and vacuum tubes.
Cesium and francium are also alkali metals. Like rubidium, the chemical properties of cesium make it useful in the manufacturing of photocells and vacuum tubes. Cesium is also a key component of research into the ion-propulsion engines used in spacecrafts. Francium, however, does not have any known real-world uses because of how rare and unstable this alkali metal is.
Alkali metals primarily occur in solid form at room temperature but may be transformed into liquids, gases and vapors. These metals vary in color but generally exist in various shades of silver and white. Alkali metals exist in pure form in nature, but they are more commonly produced and combined with other elements to form alloy substances.
Alkali metals react with certain other elements, including halogens, nitrogen and oxygen. When combined with halogens, alkali metals may be added to neon lights and signs and are combined with oxygen to form lightweight, metal substances. These metals, in turn, are used to manufacture consumer and commercial products such as cars, steel and bicycles. Some alkali metals, such as sodium and potassium, are important dietary nutrients and are found in multivitamins and certain foods.