← Back to the periodic table
Hydrogen
Reactive nonmetals · Group 1 · Period 1
Atomic properties
| Atomic number | 1 |
|---|---|
| Symbol | H |
| Standard atomic weight | 1.008 |
| Classification | Reactive nonmetals |
| Group | 1 |
| Period | 1 |
| Block | s-block |
| Electron configuration | 1s1 |
| Electronegativity (Pauling) | 2.20 |
| Common oxidation states | +1, -1 |
Physical properties
| Phase at 20 °C | Gas |
|---|---|
| Density | 0.00008988 g/cm³ |
| Melting point | -259.16 °C |
| Boiling point | -252.87 °C |
| Discovered | 1766 |
| CAS number | — |