Rb
Rubidium is a highly reactive alkali metal that ignites spontaneously in air.
Physical Properties
| Atomic Mass | 85.468 u |
| Density | 1.532 g/cm³ |
| Melting Point | 312.46 K |
| Boiling Point | 961.0 K |
| Appearance | Silvery-white metallic |
| State at Room Temp | Solid |
Chemical Properties
| Electronegativity | 0.82 (Pauling) |
| 1st Ionization Energy | 403.0 kJ/mol |
| Electron Affinity | 46.9 kJ/mol |
| Oxidation States | +1 |
Atomic Properties
| Electron Configuration | [Kr] 5s1 |
| Atomic Radius | 248.0 pm |
| Covalent Radius | 220.0 pm |
| Van der Waals Radius | 303.0 pm |
Discovery
| Discovered By | Robert Bunsen, Gustav Kirchhoff |
| Discovery Year | 1861 |
| Location | Heidelberg, Germany |
| Named After | Latin 'rubidus' meaning deep red, from its bright red spectral lines |
About Rubidium
Rubidium is a soft, silvery-white metallic element that is the second most electropositive element. It ignites in air and reacts violently with water. It is used in atomic clocks due to its precise spectral lines.
Uses & Applications
Atomic clocks, specialty glass, fireworks (purple color), photocells, and medical imaging.
Fun Fact
Rubidium atomic clocks are so precise they would not lose a second in several hundred million years.
Isotopes
| Mass Number | Abundance | Half-Life | Stable |
| 85 | 0.7217% | - | Yes |
| 87 | 0.2783% | 49.23 billion years | No |
Electron Configuration
[Kr] 5s1