Question

Although the 4s orbitals are occupied before 3d orbital yet we cannot say that they are always more stable.explain with example

Answer 1

according to periodic table 4s is more stable than 3d because of a/c to madhliveperiodic table..

Answer 2

Explanation:

Electrons fill the low energy orbitals before they start filling the high energy orbitals. Since the 4s orbitals are low in energy as compared to 3d orbitals, these are filled by electrons first and to full capacity.

However, the 4s orbitals may not be as stable as 3d orbitals that have high energy and may only be half-filled by electrons. This is because according to Hund Rule, half-filled orbitals are always more stable.

For example, $4p^3$ orbital is more stable than the $3d^2$ orbital.