This article explains the Electronic Configuration of Chromium and how to write the Electronic Configuration of Chromium atom (Cr).
Electronic Configuration of Chromium
Electronic Configuration of Chromium Atom (Cr) (Atomic Number 24)
The atomic number of Chromium (Cr) = 24
So, let’s start writing the electronic configuration of Chromium (Cr) based upon the Aufbau Principle. According to Aufbau Principle, “the orbitals are filled up with electrons in order of their increasing energy, i.e., orbital of lowest energy are filled up first, and those with the highest energy are filled up at the end.”
- According to Aufbau Principle, the first two electrons of Chromium (Cr) are filled in 1s orbital.
- Then, the next two electrons for Chromium occupy in the 2s orbital.
- And, next 6 electrons for Chromium occupy in the 2p orbital.
- Then, the next two electrons go in the 3s.
- Further, the next 6 electrons occupy the 3p orbital.
- Now, by following the same rule of the Aufbau Principle, within the remaining 6 electrons, two electrons are placed in 4s orbital, and 4 electrons are placed in the 3d orbital. Thus, the expected electronic configuration of Chromium (Cr) will be as follows:
The expected electronic configuration of Chromium: 1s22s22p63s23p6 3d4 4s2
However, half–filled or fully-filled orbitals are more stable due to the symmetrical distribution of electrons. Therefore, one of the 4s2 electrons of the Chromium atom jumps to the 3d5 to achieve a half-filled 3d orbital. Thus, the correct electronic configuration of the chromium atom will be as follows:
The correct electronic configuration of Chromium: 1s22s22p63s23p6 3d5 4s1
Electronic configuration of Chromium atom (24): 1s22s22p63s23p6 3d5 4s1
This electronic configuration also can be written as [Ar] 3d5 4s1
Electronic Configuration of Cr2+ (Atomic Number 22)
The atomic number of the Cr2+ is 22.
The electronic configuration of Cr2+: 1s22s22p63s23p6 3d4 4s0
Electronic Configuration of Cr3+ (Atomic Number 21)
The atomic number of the Cr3+ is 21.
The electronic configuration of Cr3+: 1s22s22p63s23p6 3d3 4s0