Rubidium Electron Configuration:7 Easy Steps on How to Write

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There are 118 identified elements in the periodic table. In this article, we are talking about one such element.

The electronic configuration of Rubidium is: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1. Rubidium(Rb) is an alkali metal present in the fifth row of the table, having higher density than water. Identified for its silvery texture, Rb is reactive to water and air and hence often kept sealed.Oxidation state of +1 is common in Rb.

Let us cover the interesting electron density and distribution of electrons in Rb in this article.

How to write Rubidium Electron Configuration?

The atomic number of Rb is 37 which is also the number of electrons present in it. The electronic structure is defined by certain rules. These are as follows:

Step 1: List the energy order of the orbitals

All electron-filled atomic orbitals are in a specific energy order sequence following the Aufbau principle that observes the (n+l) rule where n= principal quantum number(refers to 1,2 etc.) and l= Azimuthal quantum number(refers to s,p etc.).For Rubidium, the energy order is: 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s

Step 2: Follow the rule of electron filling in each orbital

Only two electrons constitute an orbital with different spins, as per Pauli’s exclusion principle. For example, s-orbital holds two electrons, p orbitals hold net six electrons and d-orbitals hold net ten electrons. The electrons are to be noted as superscripts in the arrangement of the ordered orbitals.

Step 3: Arrangement of electrons in all the orbitals

Each orbital of the “sub-level” must be filled before pairing electrons, as per Hund’s rule. The resultant electronic configuration is: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1

Rubidium Electron Configuration Diagram

Rb has the following orbital characteristics:

  • Total orbitals of all sub-levels- 19
  • Total energy levels- 9
Sub-shellNumber of Orbitals
s1
p3
d5
Orbital Information
Aufbau1 ch
Energy Order Series of Orbitals

Rubidium Electron Configuration Notation

Rb37 Electronic Configuration- [Kr36] 5s1

A smaller notation defining electronic configuration with respect to Nobel gas is also used. Around 36 electrons are present in Krypton while rest 8 electrons combined give Rubidium.

Rubidium Unabbreviated Electron Configuration

Rb unabbreviated form can be written as 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 .

Ground State Rubidium Electron Configuration

In the ground state, the Rb electronic configuration is written as 1s2 2s2 2px2 2py2 2pz2 3s2 3px2 3py2 3pz2 4s2 3dxy2 3dyz2 3dxz2 3d2x2-y2 3dz22 4px2 4py2 4pz2 5s1.

  • The first orbital filled is 1s orbital with least energy followed by 2s and p orbital series till 3p orbitals.
  • Though 3d has lower n=3, 4s gets filled before 3d as it has lower energy by (n+l) formula.
  • The principal quantum number n increases as we climb up the energy series and finally the electron configuration ends at 5s.

Excited State of Rubidium Electron Configuration

In the excited state Rb electron configuration can be written as 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4px2 4py2 4pz1 5s2. When exiting the atom, the electron jumps from a lower energy orbital to the next higher energy orbital. Possible other configurations are as follows:

  • 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4px1 4py2 4pz2 5s2
  • 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4px2 4py1 4pz2 5s2

Ground State of Rubidium Orbital Diagram

In the ground state of Rb, the electrons are arranged following the classical rules of filling according to the increasing order of energies.

Energy order1 ch
Orbital Energy Picture of Rb

Rubidium Condensed Electron Configuration

The Rb condensed electronic configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 which is the same as the ground state configuration, with the electrons following all the energy ordering rules.

Rubidium Chloride Electron Configuration

Rubidium Chloride (RbCl) is an ionic compound formed by the complete transfer of an electron from the 5s orbital of Rb to the 3p orbital of Cl.

  • Rb elemental electronic configuration- [Kr36] 5s1
  • Cl  elemental electronic configuration- [Ne10] 3s2 3p5
  • Rb compound electronic configuration- [Kr36] 5s0
  • Cl  compound electronic configuration- [Ne10] 3s2 3p6
  • Rb electronic configuration matches that of Kr.
  • Cl electronic configuration matches that of Ar (atomic number- 18)

Conclusion

Rubidium is an element of group 1 of the periodic table. It has a large Van der Waals radius of 303 pm. The electronic configuration explains the formation of compounds like Rubidium chloride, which is used as biomarkers in living cells.

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