(b) Would you expect it to require more or less energy to remove a 3s electron from the chlorine atom, as compared with a 2p electron?

Key Concepts

Electron Shells and Energy Levels

Electrons in an atom are arranged in shells or energy levels, with each shell corresponding to a specific distance from the nucleus. The 2p electrons are in a lower energy level (n=2) compared to the 3s electrons (n=3). Generally, electrons in higher energy levels are further from the nucleus and experience less effective nuclear charge, making them easier to remove.

Effective Nuclear Charge (Z_eff)

Effective nuclear charge refers to the net positive charge experienced by an electron in a multi-electron atom. It accounts for the shielding effect of inner electrons that reduce the full nuclear charge. In chlorine, the 3s electron experiences a lower Z_eff compared to the 2p electron due to increased shielding, which influences the energy required for electron removal.

Ionization Energy

Ionization energy is the energy required to remove an electron from an atom in its gaseous state. It generally increases with higher nuclear charge and decreases with increased electron shielding. Since the 3s electron in chlorine is further from the nucleus and experiences more shielding than the 2p electron, it requires less energy to remove, leading to a lower ionization energy for the 3s electron.