Final answer:
Excited states of atoms are represented by electron configurations where electrons occupy higher energy levels than in the ground state. Filled valence shells indicate stability and a ground state configuration, while half-filled orbitals and aligned electron spins can also be part of a ground state configuration under certain circumstances.
Step-by-step explanation:
An excited state of an atom refers to any state where an electron is at a higher energy level than the ground state. Therefore, the correct option that represents excited states in neutral atoms is B) Configurations where electrons occupy higher energy levels than the ground state.
In the ground state, electrons fill the lowest available energy levels first. However, when an electron absorbs energy, for instance through radiation or light, it can be excited to a higher energy level, which does not follow this normal order. This is seen when elements such as chromium (Cr) and copper (Cu) exhibit unusual ground state electron configurations due to the stability provided by half-filled or completely filled subshells.
It's important to note that configurations with filled valence shells are typically the most stable and represent the ground state, not an excited state. Configurations with electron spins aligned or with half-filled orbitals do not necessarily represent excited states; these can often be ground states due to the stability conferred by specific electron arrangements, as is the case with Cu or Cr.