Rubidium (Rb) - Element 37 | Properties & Electron Configuration
What is Rubidium?
Rubidium (Rb) is element 37, a alkali metal in period 5, group 1. Its electron configuration is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 5s¹.
| Atomic Number | 37 |
| Symbol | Rb |
| Atomic Mass | 85.468 u |
| Category | Alkali Metal |
| Period | 5 |
| Group | 1 |
| Block | s |
| Electron Configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 5s¹ |
| Short Config | [Kr] 5s¹ |
| Electronegativity | 0.82 |
| Atomic Radius | 235 pm |
| Ionization Energy | 403 kJ/mol |
| Electron Affinity | 47 kJ/mol |
| Phase (STP) | Solid |
Electron Configuration
The full electron configuration of Rubidium is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 5s¹. In noble gas shorthand, this is written as [Kr] 5s¹.
Rubidium is a s-block element in group 1, period 5.
Periodic Trends
Electronegativity: Rubidium has a Pauling electronegativity of 0.82. Within group 1, electronegativity generally decreases down the group.
Atomic Radius: 235 pm. Across period 5, atomic radius generally decreases left to right as nuclear charge increases.
Ionization Energy: 403 kJ/mol. Ionization energy generally increases across a period and decreases down a group.
View all 118 elements with trend overlays for electronegativity, atomic radius, ionization energy, and electron affinity.
Explore Rubidium on the Interactive Periodic TableRelated Topics
Hydrogen (H)
Properties of Hydrogen - same group as Rubidium
Lithium (Li)
Properties of Lithium - same group as Rubidium
Sodium (Na)
Properties of Sodium - same group as Rubidium
Strontium (Sr)
Properties of Strontium - same period as Rubidium
Yttrium (Y)
Properties of Yttrium - same period as Rubidium
Zirconium (Zr)
Properties of Zirconium - same period as Rubidium