Hydrogen is the first element on the periodic table, it has many unique properties and is the most stable element.
| Colour | Colourless |
| Phase | Gas |
| Density | (0C, 101.325 kPa) 0.08988 g/L |
| Liquid density at melting point | 0.07 (0.0763 solid) gcm^-3 |
| Liquid density at boiling point | 0.07099 gcm^-3 |
| Melting point | 14.01 K,-259.14 C,-434.45F |
| Boiling point | 20.28 K,-252.87 C,-423.17 F |
| Triple point | 13.8033 K (-259C), 7.042 kPa |
| Critical point | 32.97 K, 1.293 MPa |
| Heat of fusion | (H2) 0.117 kJ mol^-1 |
| Heat of vapoization | (H2) 0.904 kJ mol^-1 |
| Molar heat capacity | (H2) 28.836 J mol^-1 K^-1 |
