What is the electronic configuration of copper?

Correct option is D

The correct answer is (d) 3d¹⁰ 4s¹.
Explanation:
Copper (Cu) has an atomic number of 29. In most cases, elements fill their orbitals in such a way that they follow the expected order of increasing energy levels. However, copper is an exception due to the stability associated with a completely filled 3d subshell.
Instead of following the expected configuration of 3d⁹ 4s², copper adopts the configuration 3d¹⁰ 4s¹. This arrangement provides a more stable, lower-energy state because a completely filled d-orbital (3d¹⁰) is more stable than a partially filled one.
Electronic Configuration of Copper:
· Expected: 3d⁹ 4s²
· Actual: 3d¹⁰ 4s¹ (due to enhanced stability from a fully filled 3d subshell)
Information Booster: ● Copper and chromium are notable exceptions to the expected filling order of orbitals. ● A completely filled d-orbital (3d¹⁰) or half-filled d-orbital (3d⁵ in chromium) provides extra stability. ● This stability adjustment is due to electron-electron interactions and exchange energy in the d-orbitals. ● Transition metals often exhibit unique electron configurations due to these stability factors.