Answer:
[Ar] 4s² 3d⁵ or 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵
Explanation:
Manganese electronic configuration is [Ar] 3d⁵ 4s². Manganese has 5 electrons in its 3d shell and all five electrons and unpaired maintaining parallel spin since they must obey hund's rule.
Generally electrons first enter 4s² shell filling it first before entering the 3d shell due to the lower energy 4s orbital has compared to 3d orbital. Filling of the 3d orbital must be filled parallel first before pairing begins. However in the case of manganese, it only has five electrons in its 3d orbital which will only fill it with single spins.
Due to the fact that manganese has five electrons in its 3d orbital its highly magnetic and its classified as a "ferromagnetic" substance.
Note when manganese forms a bond, it loses electrons from its 4s orbital too first to form Mn(ii) or combined from both 4s and 3d to form Mn(iii), (iv) (vi) etc.
Attached is a diagram showing how manganese atoms are arranged in its shells
