| General |
|---|
| Name | Hydrogen | | Symbol | H | | Number | 1 | | Chemical series | | | Group / Period | 1 / 1 | | Block | s-block | | CAS registry number | 1333-74-0 |
| Physical properties |
|---|
| State | gas | | Density | 0.08988 g/L | | Melting point | 14.01 K (−259.14 °C, −434.45 °F) | | Boiling point | 20.28 K (−252.87 °C, −423.17 °F) | | Critical point | 32.97 K, 1.293 MPa |
| Atomic properties |
|---|
| Atomic Weight | 1.00794 g/mol | | Crystal structure | hexagonal | | Electronegativity | 2.20 | | Atomic radius | 25 pm | | Atomic radius (calculated) | 53 pm | | Electron configuration | 1s1 | | Electrons per shell | 1 | | Number of protons | 1 | | Number of neutrons | 0 |
|
Helium