Césium (Cs)
Césium is the chemical element with atomic number 55 and symbol Cs. It is a métal alcalin in period 6, group 1, with a standard atomic weight of 132.91 u.
Faits essentiels
- Z
- 55
- Atomic weight
- 132.91 u
- Category
- métal alcalin
- State at 298 K
- Solid
- Occurrence
- primordial
- Discovered
- 1860
- CAS
- 7440-46-2
Propriétés mesurées
| Property | Value | Source |
|---|---|---|
| Electronegativity | 0.79 | National Center for Biotechnology Information (NIH) |
| Melting point | 301.59 K | National Center for Biotechnology Information (NIH) |
| Boiling point | 944 K | National Center for Biotechnology Information (NIH) |
| Density stp | 1.93 g/cm³ | National Center for Biotechnology Information (NIH) |
| Atomic radius empirical | 343 pm | National Center for Biotechnology Information (NIH) |
| Ionization energy 1st | 375.7 kJ/mol | National Center for Biotechnology Information (NIH) |
| Electron affinity | 45.5 kJ/mol | National Center for Biotechnology Information (NIH) |
Configuration électronique
- Noble gas notation
- [Xe] 6s¹
- Full notation
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 6s¹
- Electrons per shell
- 2, 8, 18, 18, 8, 1