Lighter vehicles that are designed for consumers, as well as the industry and military sectors, consume less fuel and provide a better performance. In addition to carrying larger loads, lighter vehicles can travel the same distances at reduced cost and release less carbon dioxide. In light metal hydroxide systems, hydrogen desorption generally occurs in exo- thermic reactions. Aluminum is a soft and lightweight metal. It has a dull silvery appearance, because of a thin layer of oxidation that forms quickly when it is exposed to air. A light metal is any metal of relative lower density like Magnesium, aluminium and titanium are light metals of significant commercial importance. The lightest metal that is a pure element is lithium, which has a density of 0.534 g/cm3. This makes lithium nearly half as dense as water, so if lithium was not so reactive, a chunk of the metal would float on water. Two other metallic elements are less dense than water. The most important light metals are aluminum, magnesium, titanium, beryllium, and lithium. Light metal and alloys possess high strength-to-weight ratios and low density, and are generally defined by low toxicity as opposed to heavy metals, except for beryllium.