Answer:-

The electronic configurations of chromium (Cr) and copper (Cu) are exceptions to the normal filling order of electron orbitals due to their stability when having a half-filled or fully-filled d subshell. Here are their electronic configurations:

1. Chromium (Cr):
   • The atomic number of chromium is 24.
   • The ground-state electron configuration of chromium is: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵.
   • Chromium is an exception because it has one electron in the 4s orbital and five electrons in the 3d orbitals. This configuration provides greater stability due to the half-filled 3d subshell, which is more stable than having an additional electron in the 4s orbital.

So, the shorthand electron configuration of chromium is [Ar] 3d⁵ 4s¹.

2. Copper (Cu):
   • The atomic number of copper is 29.
   • The ground-state electron configuration of copper is: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁹.
   • Copper is also an exception because it has one electron in the 4s orbital and nine electrons in the 3d orbitals. This configuration provides greater stability due to the fully-filled 3d subshell, which is even more stable than having an additional electron in the 4s orbital.

So, the shorthand electron configuration of copper is [Ar] 3d⁶ 4s².