Osmium introduced commercially in 1902. After only a few years, osmium was replaced by the more stable metal tungsten. Tungsten has the highest melting point among all metals, and its use in light bulbs increases the luminous efficacy and life of incandescent lamps. The light bulb manufacturer Osram (founded in 1906, when three German companies, Auer-Gesellschaft, AEG and Siemens & Halske, combined their lamp production facilities) derived its name from the elements of osmium and Wolfram (the latter is German for tungsten). Like palladium, powdered osmium effectively absorbs hydrogen atoms. This could make osmium a potential candidate for a metal-hydride battery
Period 4 element quickly begins to tarnish as it reacts with air. It is soft enough to be cut with a knife and it is the second least dense element. Potassium has a relatively low melting point; it will melt just by putting it under a small open flame. It also is less dense than water, and can, in turn, float. Calcium (Ca) is the second element in period 4, between potassium and scandium. An alkali earth metal, calcium is almost never found in nature due to its high reactivity with water. It has one of the most widely known and acknowledged biological