Properties of hydrogen
Hydrogen is an odourless, colourless gas. It is highly flammable and combines readily with oxygen to form water. When hydrogen is mixed with air it forms an explosive mixture that ignites with a single spark. It is such a powerful fuel that the main engines of the space shuttle are fuelled by hydrogen.
| Symbol: | H |
| Atomic number: | 1 |
| Relative atomic mass: | 1 |
| Electronic configuration: | 1s1 |
| Molecular formula: | H2 |
| Relative molecular mass: | 2 |
| Boiling point: | 20 K |
| Key properties: | Low density and highlly flammable, Reducing Agent. |
| Some major uses: | Feedstock for chemical production, fuel for fuel cells and rocket engines, removing oxygen during glass making. |
| Discoverer: | Henry Cavendish (1766) |
Hydrogen all around us
Hydrogen is the most abundant element in the universe. About 93 per cent of all the atoms in the universe are hydrogen atoms. But it is the lightest element, so it forms about 76 per cent of the mass of the universe. Hydrogen is also the most abundant element in the Sun but it only forms 0.14 per cent of the Earth's crust. Water is a compound of hydrogen and oxygen. Water is the most abundant compound on the Earth's surface and covers about two-thirds of it.
The atmosphere only contains a tiny proportion of hydrogen gas, about 1 part per million (0.0001 per cent). However, air contains much more water vapour. In very humid places the air can contain about 6 per cent water vapour, while in a desert it might contain as little as 0.1 per cent water vapour. Industry gets most of its hydrogen from natural gas or steam.
Laboratory test for hydrogen
Place a lighted splint into a test tube of hydrogen. The gas ignites with a squeaky pop.
