H
Hydrogen is the lightest and most abundant element in the universe, making up about 75% of all normal matter by mass.
Physical Properties
| Atomic Mass | 1.008 u |
| Density | 0.00008988 g/cm³ |
| Melting Point | 14.01 K |
| Boiling Point | 20.28 K |
| Appearance | Colorless gas |
| State at Room Temp | Gas |
Chemical Properties
| Electronegativity | 2.2 (Pauling) |
| 1st Ionization Energy | 1312.0 kJ/mol |
| Electron Affinity | 72.8 kJ/mol |
| Oxidation States | -1, +1 |
Atomic Properties
| Electron Configuration | 1s1 |
| Atomic Radius | 25.0 pm |
| Covalent Radius | 31.0 pm |
| Van der Waals Radius | 120.0 pm |
Discovery
| Discovered By | Henry Cavendish |
| Discovery Year | 1766 |
| Location | London, England |
| Named After | Greek 'hydro' and 'genes' meaning water-forming |
About Hydrogen
Hydrogen is a colorless, odorless, tasteless, and highly flammable gas. It is the simplest element with just one proton and one electron. Stars like our Sun are primarily powered by hydrogen fusion reactions. On Earth, hydrogen is mostly found combined with oxygen in water.
Uses & Applications
Rocket fuel, petroleum refining, ammonia production, fuel cells, welding, and as a potential clean energy carrier.
Fun Fact
Hydrogen is the only element whose isotopes have individual names: protium, deuterium, and tritium.
Isotopes
| Mass Number | Abundance | Half-Life | Stable |
| 1 | 0.999885% | - | Yes |
| 2 | 0.000115% | - | Yes |
| 3 | - | 12.32 years | No |
Electron Configuration
1s1