Stars are fuelled by hydrogen. At incredibly high temperatures inside stars, hydrogen atoms smash into one another and fuse (join) together to create helium atoms. These reactions give out a huge amount of energy as light and heat. Hydrogen atoms were probably the first atoms to form in the Universe and fuse together to create other, heavier atoms.

The space shuttle uses liquid hydrogen fuel because hydrogen gives out a lot of power for very little weight. Hydrogen, like all fuel, needs oxygen to burn, so the shuttle has a tank of liquid hydrogen and a tank of liquid oxygen. A fine mist of the two liquids is sprayed into the engines and ignited (set alight). The hydrogen explodes, sending steam out of the nozzles and helping to thrust the shuttle into space.

Margarine is made by passing bubbles of hydrogen gas through hot vegetable oil. Extra hydrogen atoms bond (join) with the oil molecules, and the oil changes from a liquid to a more solid form. This process is called hydrogenation. If oil is fully hydrogenated, it becomes completely solid; by stopping part way, it becomes a semi-solid.

Scientists are developing hydrogen-powered cars. The cars contain tanks of hydrogen that combine with oxygen from the air to drive them. Hydrogen-fuelled cars produce water instead of polluting exhaust gases. They are not mass-produced, because scientists have not developed a compact and lightweight method for storing hydrogen yet.

This chemist is often known as the father of modern chemistry. He studied the “inflammable air” that was discovered by English scientist Henry Cavendish (1731–1810). Lavoisier discovered that this gas combines with oxygen to make water. He named the gas hydrogen, which is Greek for water-former.