 Discovery Information |
| Who:
Henry Cavendish
|
| When: 1766 |
| Where: England |
|
| Name Origin |
| Greek: hudor (water) and gennan (generate) |
|
| Sources |
| Found chiefly combined with oxygen in the form of water, also found in mines and oil and gas wells. Stars contain a virtually unlimited supply hydrogen and in the universe, hydrogen is the most abundant element (hydrogen makes up 75% of the mass of the visible universe and over 90% by number of atoms.). |
|
| Uses |
| Hydrogen's uses include: being used in the production of ammonia, ethanol, hydrogen chloride and hydrogen bromide; the hydrogenation of vegetable oils; hydrocracking, hydroforming and hydrofining of petroleum; atomic-hydrogen welding; instrument-carrying ballons; fuel in rockets; and cryogenic research. Its two heavier
isotopes
, deuterium (D) and tritium (T), are used respectively for nuclear fission and fusion. |
|
| Notes |
| Hydrogen is a tasteless, colorless, odorless and extremely flammable gas, it is also the lightest chemical element. |
| At
standard temperature and pressure
, hydrogen exists as the diatomic gas, H2, with a boiling point of 20.27 K, and a melting point of 14.02 K. Under extreme pressures, such as those at the center of gas giants, the
molecules
lose their identity and the hydrogen becomes a metal (metallic hydrogen). Under the extremely low pressure in space - virtually a vacuum - the element tends to exist as individual atoms, simply because it is statistically unlikely for them to combine. |
| A unique property of hydrogen is that its flame is nearly invisible in air. |
