Sample of the element tungsten W rotating. Tungsten has the atomic number 74, and is a grey, dense, hard metal. It is used extensively in steel alloys and in materials such as tungsten carbide, which are both used for their hardness. Tungsten is also used in filament light bulbs and thermionic valves due to its high melting point, which at 3422 degrees Celsius is the highest of the metals, and the second highest of any element, after carbon.