The ground state electronic configuration of chromium atom is:
The ground state electronic configuration of chromium atom is:
The correct option is A
Atomic number of Chromium = 24
[Ar]=1s2 2s2 2p6 3s2 3p6
Hence, Cr=[Ar]3d5 4s1
It is an exception to normal filling of orbitals in an atom.
The ground state electronic configuration of the atom of an element always corresponds to the state of the lowest total electronic energy. In case of Cr and Cu, where the two subshells (4s and 3d) differ slightly in their energies, an electron shifts from a subshell of lower energy (4s) to a higher energy (3d), provided such a shift results in all orbitals of the subshell of higher energy getting either completely filled or half filled.
Half-filled and fully-filled sub-shells are extra stable in these configurations
This is because of the concept of Exchange Energy and symmetrical distribution of electrons. what is exchange energy?
Exchange energy:- Exchange means shifting of electrons from one orbital to another within the same sub-shell.Energy is released when electrons exchange their postition and is called the exchange energy.The maximum the number of exchanges, the maximum the energy released and the maximum the stabilisation.Half-filled and fully filled degenerate orbitals have more number of exchanges,and consequently,they ahve larger energy of stabilisation.
For example,chromium atom with configuration 3 d5 4s1 has higher exchange compared to the configuration of 3d4 4 s2
Total exchanges = 3 + 2 + 1 = 6
Thus, in 3d4 arrangement, total electron exchanges are six, which implies that there are six possible arrangements with parallel spin in 3d1 configuration.
Total exchanges = 4 + 3 + 2 + 1 = 10
It is clear from the above description that the total number of electron exchanges in 3d arrangement is larger, which gives it relatively greater stability.
Atomic number of Chromium = 24
[Ar]=1s2 2s2 2p6 3s2 3p6
Hence, Cr=[Ar]3d5 4s1
It is an exception to normal filling of orbitals in an atom.
The ground state electronic configuration of the atom of an element always corresponds to the state of the lowest total electronic energy. In case of Cr and Cu, where the two subshells (4s and 3d) differ slightly in their energies, an electron shifts from a subshell of lower energy (4s) to a higher energy (3d), provided such a shift results in all orbitals of the subshell of higher energy getting either completely filled or half filled.
Half-filled and fully-filled sub-shells are extra stable in these configurations
This is because of the concept of Exchange Energy and symmetrical distribution of electrons. what is exchange energy?
Exchange energy:- Exchange means shifting of electrons from one orbital to another within the same sub-shell.Energy is released when electrons exchange their postition and is called the exchange energy.The maximum the number of exchanges, the maximum the energy released and the maximum the stabilisation.Half-filled and fully filled degenerate orbitals have more number of exchanges,and consequently,they ahve larger energy of stabilisation.
For example,chromium atom with configuration 3 d5 4s1 has higher exchange compared to the configuration of 3d4 4 s2
Total exchanges = 3 + 2 + 1 = 6
Thus, in 3d4 arrangement, total electron exchanges are six, which implies that there are six possible arrangements with parallel spin in 3d1 configuration.
Total exchanges = 4 + 3 + 2 + 1 = 10
It is clear from the above description that the total number of electron exchanges in 3d arrangement is larger, which gives it relatively greater stability.
