The heaviest elements

Osmuim
Osmium is the heaviest element of all (22.61g per cubic centimeter). It was discovered by the British chemist Smithson Tennant in 1803. He named it after the Greek word for smell because it smelt bad. Osmium is twice as heavy as lead – so heavy that a cubic foot (0.028317 cubic meters) weighs 640ks, as much as ten average people! A football made of osmium would weigh 126 kg, or much as two adults. Osmium is also very hard, and is used to make hard-wearing points, such as the nibs of fountain pens.

Platinum
Platinum was used before anyone realized that it was an element. It weighs almost as much as osmium (21.45g per cubic centimeter) and is also used in catalytic converters in cars to reduce the pollution from exhaust gases.

Plutonium
Plutonium was discovered in 1941 and is heavy and highly radioactive metal. It is used as a nuclear fuel and in nuclear weapons - a kilogram of plutonium produces an explosion equivalent to 20,000 tonnes of TNT.