H

H is a pure elemental metal with an extremely low density, positioning it as one of the lightest metallic materials available. It finds use in aerospace, automotive, and specialized applications where weight reduction is critical, though its industrial adoption is limited by challenges in processing, cost, and material stability compared to conventional lightweight metals like aluminum or magnesium. Engineers typically consider H for experimental structures, hydrogen storage systems, or niche applications requiring exceptional lightness, though practical alternatives often dominate due to superior manufacturability and established supply chains.