Question

what are the exception for wrting electron configuration?

Answer 1

Some exception in writing electron configuration to the Aufbau rule.

According to Aufbau rule, electrons are filled in orbitals in order of increasing atomic number.

The exceptions in writing electron configuration of some transition metals and heavier elements. This is due to some elements are more stable with fewer electrons in some subshells and more electrons in others.

Exceptions to electron configuration of chromium and copper are as follows;

Cr: [Ar] 3d⁵4s¹

Cu: [Ar] 3d¹⁰4s¹