Osmium
... 23 (3) g Number of Protons/Electrons: 76 Number of Neutrons: Electron configuration: Physical Properties: Density: 22610 kg/m3 Boiling point [/K]: 5285 [or 5012 °C (9054 °F)] (liquid range: 1979 K) Melting point [/K]: 3306 [or 3033 °C (5491 °F)] Chemical reactions of the elements Reaction of osmium with air Osmium is largely immune to atmospheric attack. On heating with oxygen, osmium metal gives the rather volatile (melting point 30°C, boiling point 130°C) osmium (VIII) oxide, OsO4.