## Chemistry: The Central Science (13th Edition)

The orbitals in order of increasing energy for the hydrogen atom are: $$2s = 2p<3s<4d<5s$$
- In hydrogen atom, since there is only 1 electron, the energy of an orbital depends entirely on the value of $n$. That means, any orbitals in the same shell have the same energy. Remember that this fact is only true for an one-electron system like the hydrogen atom. (For example, the energy of orbital $2s$ is the same as that of orbital $2p$) - As you might recall, to move an electron from a lower shell to a higher shell requires an energy input. Therefore, the energy of an orbital in a lower shell is lower than that in a higher shell. (For example, the energy of orbital $2s$ is lower than that of orbital $3d$) Overall, the orbitals in order of increasing energy for the hydrogen atom are: $$2s = 2p<3s<4d<5s$$