Electronic Configurations The aufbau principle Relative orbital energies states to fill the lowest 12px 12p -2p. energy orbitals first. Hund's rule states that energy when there are two or more orbitals of the same energy 1s (degenerate),electrons will go into different orbitals Electronic configuration of carbon rather than pairing up in the same orbital. Chapter 1 7 Chapter 1 7 Electronic Configurations • The aufbau principle states to fill the lowest energy orbitals first. • Hund’s rule states that when there are two or more orbitals of the same energy (degenerate), electrons will go into different orbitals rather than pairing up in the same orbital. Electronic configuration of carbon