the ion Na+ and the atom Ne have the same electron configuration. to remove an electron from the gaseous neon atom requires 2081 kj/mol. to remove an electron from a gaseous Na+ ion requires 4562 kj/mol. why are these values not the same?
The values for ionization energy, which is the energy required to remove an electron, differ for Na+ and Ne due to their different electron configurations and atomic structures.
To explain why the values are not the same, we need to understand the electron configurations of Na+ and Ne.
The electron configuration of sodium (Na) is 1s² 2s² 2p⁶ 3s¹, which means it has 11 electrons distributed in its various energy levels. When Na loses one electron to form the Na+ ion, its electron configuration becomes 1s² 2s² 2p⁶, which is the same electron configuration as neon (Ne).
The electron configuration of neon (Ne) is 1s² 2s² 2p⁶, which means it has 10 electrons. Since both Na+ and Ne have the same electron configuration, we might expect their ionization energy values to be the same. However, that's not the case, and the values differ because of the following reasons:
1. Effective nuclear charge: The ionization energy is influenced by the attractive force between the protons in the nucleus and the electrons. In Na+, there are still 11 protons but only 10 electrons, so the effective nuclear charge increases. This stronger attractive force requires more energy to remove an electron from Na+ compared to Ne.
2. Electron shielding: Electron shielding refers to the repulsion between electrons in different energy levels. In Na+, the 10 remaining electrons shield the outermost electron from the full effect of the increased nuclear charge. In Ne, however, all 10 electrons are in the same energy level, so there is no electron shielding. The absence of electron shielding in Ne makes it easier to remove an electron compared to Na+.
Due to these factors, the ionization energy required to remove an electron from Na+ is higher (4562 kJ/mol) compared to removing an electron from Ne (2081 kJ/mol).