Answer:
Step-by-step explanation:
The question requires us to choose, among the options given, which one correctly presents the atom with higher first-ionization energy (between Cl and Ar) and the best justification.
The first-ionization energy of an atom in the gas form corresponds to the energy required to remove a first electron from its valence shell, forming a monovalent cation.
We can analyze the first ionization energy using the electron configuration of the atoms:
- Cl contains 17 electrons, thus its electron configuration is 1s2 2s2 2p6 3s2 3p5 (7 electrons in the valence shell)
- Ar contains 18 electrons, thus its electron configuration is 1s2 2s2 2p6 3s2 3p6 (8 electrons in the valence shell)