Osmium, Physical and Chemical Properties

Osmium is a member of the group of six platinum metals which occur together in nature and is located in the center of the Periodic Table in the Iron–Cobalt–Nickel group:

Fe	Co	Ni
Ru	Rh	Pd
Osmium	Ir	Pa

Physical Properties

Osmium is a transition metal like the other members of the group. They are less reactive than the typical metals but more reactive than the less typical metals. The transition metals are characterized by having the outermost electron shell containing two electrons and the next inner shell an increasing number of electrons. Because of the small energy differences between the valence shells, a number of oxidation states occur.

Atomic number	76
Atomic weight	190.2
Relative abundance in Earth’s crust, %	1 × 10−6
Abundance of major natural isotopes	189 (16.1%)
	190 (26.4%)
	192 (41.0%)
Crystal structure	Hexagonal closed pack
Lattice constants at 20°C
a, nm	0.27341
c, nm	0.43197
Atomic radius, nm	0.134
Melting point, °C	3,045
Boiling point, °C	5,025
Specific heat at 25°C c...