The electron configurations described in this chapter all refer to gaseous atoms in their ground states. An atom may absorb a quantum of energy and promote one of its electrons to a higher-energy orbital. When this happens, we say that the atom is in an excited state. The electron configurations of some excited atoms are given. Identify these atoms and write their ground-state configurations:
(a) 1s12s1
(b) 1s22s22p23d1
(c) 1s22s22p64s1
(d) [Ar]4 s13d104p4
(e) [Ne]3s23p43d1