What is the Electron Configuration of Cr3+

What is the electron configuration of Cr³⁺? 

An element’s electronic configuration is a representation of its atoms’ electrons symbolically that are arranged across different atomic orbitals. In simple words, the electron configuration is the arrangement of electrons in distinct orbits and orbitals of an atom in a specific order.

Cr is used to represent Chromium which is the 24th element in the periodic table. Chromium is a strong, shiny metal with a silvery grey color. It’s a metal with a high melting point, a boiling point of 2672 °C, and a specific gravity of 7.18 to 7.20. The varied valencies of chromium are 2, 3, or 6.

As it contains 24 electrons in total it can be arranged correctly through the Aufbau principle by following these steps:

1. The first two electrons in Chromium’s electron configuration will be in the 1s orbital. 

2. Because the 1s orbital can only hold two electrons, Chromium’s next two electrons are assigned to the 2s orbital. 

3. Six electrons will be placed in the 2p orbital as the p orbital has a maximum capacity of six, followed by the 3s orbital with two electrons. 

4. We’ll shift to the 3p to insert the following six electrons because the 3s is now full. 

5. The remaining two electrons will now be placed in the 4s orbital. 

6. We finish with 3d⁴ by putting the remaining four electrons in the 3d orbital once the 4s is full.

7. Now the configuration(incorrect) will be 1s²2s²2p⁶3s²3p⁶3d⁴4s².

8. Subshells that are half-filled or fully filled have more stability. As a result, one of the 4s² electrons moves to the 3d⁵, which fills it halfway. 

9. Thus, we have the (correct) configuration of Cr: 1s²2s²2p⁶3s²3p⁶3d⁵4s¹.

For the electronic configuration of the Cr³⁺ ion, we will remove three electrons from the Cr (one from the 4s¹ and two from the 3d⁵), leaving us with 1s²2s²2p⁶3s²3⁶3d³ or [Ar]³d³.