Osmium
Osmium is the chemical element with symbol Os and atomic number 76.
Chemical Properties
Osmium forms compounds with oxidation state from -2 to 8. It is slightly attacked by aqua regia, and by fuming nitric acid, and it is attacked by molten hydroxides. It forms the toxic osmium tetroxide (OsO4), the most common compound with +8 oxidation state, in contact with air. It forms coordination complexes easily.
Physical Properties
It is a hard, brittle, and bluish transition metal and usually is found in traces in platinum ores. It is the densest element known, with a density of 22.6 g/cm3, slightly denser than iridium. It's almost twice as dense as lead. It melts at 3033 Cº.
Availability
It is one of the most rare elements so prices are high. It can be bought online from Metallium. It has really few applications for home chemists.
Safety
Osmium tetroxide is toxic and a powerful oxidant. Osmium powder is pyrophoric.
