Final answer:
The energy of atomic orbitals increases as the principal quantum number, n, increases. Within a given shell, the order of increasing energy for orbitals is s < p < d < f.
Step-by-step explanation:
The energy of atomic orbitals increases as the principal quantum number, n, increases. In any atom with two or more electrons, the repulsion between the electrons makes energies of subshells with different values of 1 differ so that the energy of the orbitals increases within a shell in the order s < p < d < f. For example, in the first shell, the 1s orbital has the lowest energy, followed by the 2s, then the 2p, and so on. This pattern holds true until the third period, where the 3d orbital is slightly higher in energy than the 4s orbital.