How do you write electron configurations?

Electron configuration shows how electrons fill orbitals. Follow: 1) Aufbau principle (fill lowest energy first): 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p... 2) Pauli exclusion (max 2 electrons per orbital, opposite spins). 3) Hund's rule (fill orbitals singly before pairing). Example: Carbon (6 electrons): 1s² 2s² 2p². Iron (26): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶. Shorthand uses noble gas cores: Fe = [Ar] 4s² 3d⁶.