An atom in an excited state has an electron configuration of 2-7-17-16-3. How do the second, third, and fifth shells demonstrate that this atom is in an excited state?

This configuration does NOT match 2-8-18-16-1, which is the ground-state configuration for an atom with an atomic number of 45.

Remember: To solve this kind of problem, you must first add up the electrons to find the total number of electrons. From the total number of electrons, you can find the number of protons, the atomic number, and the ground-state electron configuration from the element box. To prove that parts of an electron configuration demonstrate that the atom is in an excited state, the answer must include the ground-state configuration, the atomic number, and the fact that the configuration written in the answer is the ground-state electron configuration to begin with.