What are the different rules for filling up the orbitals? Explain each rule in detail.
What are the different rules for filling up the orbitals? Explain each rule in detail.
Order of filling of electrons in the subshell.
There are different rules governing the filling of subshells. They are described briefly as follows -
Aufbau Principle :
The filling of subshells in atoms is based on their energies. Electrons first occupy the subshell with the lowest energy and progressively fill the other subshells in increasing order of energy. The subshell with the lowest energy is filled first.
The order of energy of different subshells of an atom is -
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7p.
The number present before the subshells like 1,2,3 ------ represents the number of the shell.
Pauli’s Exclusion Principle:
According to Pauli’s exclusion principle, “an orbital cannot accommodate more than two electrons. If there are two electrons in an orbital they must have opposite spins.”
Hund’s Rule of Maximum Multiplicity:
According to this rule: “no electron pairing takes place in the orbitals with equivalent energy until each orbital in the given subshell contains one electron & the spins of all unpaired electrons are parallel i.e. in the same direction”.
Order of filling of electrons in the subshell.
There are different rules governing the filling of subshells. They are described briefly as follows -
Aufbau Principle :
The filling of subshells in atoms is based on their energies. Electrons first occupy the subshell with the lowest energy and progressively fill the other subshells in increasing order of energy. The subshell with the lowest energy is filled first.
The order of energy of different subshells of an atom is -
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7p.
The number present before the subshells like 1,2,3 ------ represents the number of the shell.
Pauli’s Exclusion Principle:
According to Pauli’s exclusion principle, “an orbital cannot accommodate more than two electrons. If there are two electrons in an orbital they must have opposite spins.”
Hund’s Rule of Maximum Multiplicity:
According to this rule: “no electron pairing takes place in the orbitals with equivalent energy until each orbital in the given subshell contains one electron & the spins of all unpaired electrons are parallel i.e. in the same direction”.
