Appearance and Characteristics
Harmful effects:
Ruthenium is a suspected carcinogen and its compounds strongly stain the skin. Ruthenium tetroxide (RuO4) is highly toxic.
Characteristics:
Ruthenium is a very rare, hard, lustrous, brittle, silvery-white metal that does not tarnish at room temperature.
Typical of transition metals, ruthenium can exist in many oxidation states, its most common being the oxidation states II, III and IV.
The metal is unaffected by air, water and acids.
It reacts with molten alkali and halogens and can oxidize explosively.
Uses of Ruthenium
Small amounts of ruthenium are used to harden platinum and palladium and it can also be alloyed with these metals to make electrical contacts for severe wear resistance.
The addition of 0.1% ruthenium improves the corrosion resistance of titanium a hundred times over.
Ruthenium has catalytic properties; for example, hydrogen sulfide can be split by light in the presence of an aqueous suspension of cadmium sulfide particles loaded with ruthenium dioxide.
Interestingly, ruthenium is used in some Parker pen nibs, such as the Parker 51 whose nib is marked ‘RU’, and consists of 96.2% ruthenium and 3.8% iridium.