Iron
Iron (26Fe) is an abundant element in the universe. It is found in the sun and many stars in quantity. Iron nuclei are very stable. Iron is a vital constituent of plant and animal, and is the key component of haemoglobin. The pure metal is not often encountered, but is usually alloyed with carbon or other metals. The pure metal is very chemically reactive, and rapidly corrodes, especially in moist air or at elevated temperatures. Any car owner knows this. Iron metal is a silvery, lustrous metal which has important magnetic properties.
Ruthenium
Ruthenium (44Ru) is a hard white metal. It does not tarnish at room temperatures, but oxidises in air at about 800°C. The metal is not attacked by hot or cold acids or aqua regia, but when potassium chlorate is added to the solution, it oxidises explosively.
Osmium
Osmium (76Os) metal is lustrous, bluish white, extremely hard, and brittle even at high temperatures. It has the highest melting point and lowest vapour pressure of the platinum group. The metal is very hard to fabricate, but the powder can be sintered in a hydrogen atmosphere at a temperature of 2000°C. The solid metal is not affected by air at room temperature, but the powdered or spongy metal slowly gives off osmium tetroxide, which is a powerful oxidising agent and has a strong smell. The tetroxide is highly toxic, and boils at 130°C (760 mm). Concentrations in air as low as 10-7 g m-3 can cause lung congestion, skin damage, or eye damage.
Hassium
Hassium (108Hs) is a radioactive synthetic element that is not present in the environment at all.
