The orbitals in which the sub-shell is exactly half-filled or completely filled are more stable because of the symmetrical distribution of electrons. ... When the orbitals are half-filled or completely filled then the number of exchanges is maximum. Therefore, its stability is maximum.

Why half and fully filled subshells are stable?

- We know that half-filled or fully filled atomic orbitals have more symmetry than any other electronic configuration and this symmetry leads to the greater stability of the atom. ... - The reason behind stability of the half-filled and fully filled electrons in orbitals is symmetry and exchange energy of the electrons.

Which Subshell is most stable?

Full - filled p-orbital is more stable than full - filled d-orbitals, i.e. p6>d10. Similarly, half -filled p-orbital is more stable than half - filled d-orbital, i.e. p3>d5.