| Quantity | Value | Units | Value | Units |
| Atomic number | 19 | |||
| Atomic mass | 39.0983(1) | g mole-1 | ||
| Density | 0.862 | g cm-3 | ||
| Mean excitation energy | 190.0 | eV | ||
| Minimum ionization | 1.623 | MeV g-1cm2 | 1.399 | MeV cm-1 |
| Nuclear collision length | 75.4 | g cm-2 | 87.44 | cm |
| Nuclear interaction length | 119.0 | g cm-2 | 138.0 | cm |
| Pion collision length | 101.0 | g cm-2 | 117.2 | cm |
| Pion interaction length | 148.1 | g cm-2 | 171.8 | cm |
| Radiation length | 17.32 | g cm-2 | 20.09 | cm |
| Critical energy | 31.62 | MeV (for e-) | 30.72 | MeV (for e+) |
| Molière radius | 11.61 | g cm-2 | 13.47 | cm |
| Plasma energy |
18.65 | eV | ||
| Muon critical energy | 472. | GeV |