Osmium - Os

Osmium — chemical properties and water context

Osmium is a very dense, hard, bluish-white platinum-group metal. Water professionals are most likely to encounter it in specialized metal refining or laboratory settings, rather than in ordinary source water.

Atomic number	76
Standard atomic weight	190.23 g/mol
Density	22.5872 g/cm³
Melting point	3033 °C
Boiling point	5008 °C
Electron configuration	[Xe] 4f¹⁴ 5d⁶ 6s²

Chemical properties

Osmium is in Group 8 and Period 6. It is among the densest elements and is highly resistant to corrosion. Some osmium compounds have very different properties from the metal: osmium tetroxide (OsO₄) is volatile, readily enters the air and is acutely toxic.

Uses and applications

Osmium has limited applications. It is used in certain hard alloys and as a catalyst; osmium tetroxide is used as a staining reagent in microscopy. The hazards of osmium compounds, particularly osmium tetroxide, require strict chemical-safety controls.

Osmium in water treatment

Osmium is not a routine drinking-water treatment target. If osmium is suspected in a laboratory or industrial stream, first identify the chemical form and assess whether volatile osmium tetroxide could be present. Containment, sampling and treatment must be planned by qualified hazardous-materials and process-safety personnel; ordinary filtration should not be assumed to control volatile species.

Environmental and health context

Environmental information for osmium is limited. Osmium tetroxide presents a serious inhalation and eye hazard, so preventing release and controlling exposure are central. Follow the substance-specific safety data sheet and applicable occupational and waste rules.