Question

Consider the first ionization energy of neon and the electron affinity of fluorine. (a) Write equations, including electron configurations, for each process. (b) These two quantities have opposite signs. Which will be positive, and which will be negative? (c) Would you expect the magnitudes of these two quantities to be equal? If not, which one would you expect to be larger?

Short answer

(a) Ionization energy (Neon): Ne ($1s^{2}2s^{2}2p^6$) --> Ne^+ ($1s^{2}2s^{2}2p^5$) + e^-. Electron affinity (Fluorine): F ($1s^{2}2s^{2}2p^5$) + e^- --> F^- ($1s^{2}2s^{2}2p^6$). (b) Ionization energy of neon: positive, electron affinity of fluorine: negative. (c) Magnitudes are not equal; ionization energy of neon is larger.

Step-by-step solution

a) Write equations including electron configurations for each process.

For ionization energy (Neon): Ne --> Ne^+ + e^- Electron configuration of Neon (Ne): $1s^{2}2s^{2}2p^6$ Electron configuration of Ne^+ : $1s^{2}2s^{2}2p^5$ For electron affinity (Fluorine): F + e^- --> F^- Electron configuration of Fluorine (F): $1s^{2}2s^{2}2p^5$ Electron configuration of F^- : $1s^{2}2s^{2}2p^6$

b) Identify the signs of the two quantities

Ionization energy shows how much energy is needed to remove an electron from an atom, so it will always be positive. Electron affinity represents the energy change when an electron is added to an atom, and it usually has a negative value, meaning energy is released. So, ionization energy of neon will be positive, while the electron affinity of fluorine will be negative.

c) Determine if the magnitudes of the two quantities are equal and, if not, identify which one is larger.

The magnitudes of these two quantities are not equal. The ionization energy of neon would be larger, as neon is a noble gas and has a stable electron configuration; thus, it requires more energy to remove an electron from it. On the other hand, fluorine is one electron away from a full outer shell, and it releases energy when capturing an extra electron, resulting in a negative electron affinity. Since energy is released, the magnitude will be smaller compared to the ionization energy of neon.