Question

Explain in terms of subatomic particles why an atom in an excited state is still electronically neutral when it returns to the ground state.

a) Electrons change their charge in an excited state.
b) Protons and neutrons remain unchanged.
c) Electrons move to higher energy levels temporarily.
d) The nucleus undergoes a change in charge.

Answer 1

An atom stays electrically neutral after excitation because while the electrons may move to higher energy levels temporarily in an excited state, they do not change their charge, and neither do protons and neutrons in the nucleus, maintaining electrical neutrality.

Step-by-step explanation:

An atom remains electrically neutral when it returns to the ground state after being in an excited state because the number of protons and electrons remains unchanged. The statement b) Protons and neutrons remain unchanged is correct. Excitation occurs when electrons absorb energy and move to higher energy levels temporarily; however, they do not change their charge. In an excited state, the electron has higher potential energy and is unstable. As the excited electron returns to the ground state, it emits a photon, releasing the excess energy it had absorbed, but it is still the same electron with a negative charge. Since the total number of positive charges (protons) and negative charges (electrons) remains equal, the atom as a whole stays neutral.