Question

(c.6b) many people believe that the atomic number of the atom is the number of electrons in the atom. describe when this is the case. as the atom absorbs photons the electrons excite and produce unique emission spectrum. whether the atom is neutral or charged the number of electrons is always a unique identifier. through radioactive decay the electrons and neutrons form unique atomic number isotopes. when the atom is neutral and the number of electrons and the number of protons are equal

Explanation:

To determine when the atomic number (number of protons) equals the number of electrons in an atom, we analyze each option:

1. First option: Absorbing/emitting photons relates to electron energy levels (spectra), not electron - proton balance. Eliminate.
2. Second option: Electron count for charge (neutral/charged) determines charge, but the question is about when \( \text{protons}=\text{electrons} \), not about electron count as an identifier. Eliminate.
3. Third option: Radioactive decay (changing neutrons/electrons) creates isotopes, not about proton - electron equality. Eliminate.
4. Fourth option: By definition, a neutral atom has no net charge. Since protons are positive and electrons are negative, their numbers must be equal (\( \text{protons}=\text{electrons} \)) to cancel out charges.

Answer:

When the atom is neutral and the number of electrons and the number of protons are equal.