Problem 53 - Chemistry: The Central Science

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?

Step-by-Step Solution

Answer

(a) Ionization energy of Ne: \(Ne(g) \rightarrow Ne^{+}(g) + e^-\), Electron affinity of F: \(F(g) + e^- \rightarrow F^-(g)\). (b) Ionization energy of Ne is positive, electron affinity of F is negative. (c) Magnitudes are not equal; first ionization energy of Ne is expected to be larger than the electron affinity of F.

Step 1: (a) Electron configurations and ionization energy of neon and electron affinity of fluorine

To analyze the processes, we first need to write the electron configurations for neon (Ne) and fluorine (F). - Neon (Ne) has an atomic number of 10, and its electron configuration is 1s² 2s² 2p⁶. - Fluorine (F) has an atomic number of 9, and its electron configuration is 1s² 2s² 2p⁵. Now, let's write the equations for the first ionization energy of Ne and the electron affinity for F. Ionization energy of Ne: \(Ne(g) \rightarrow Ne^{+}(g) + e^-\) Electron affinity of F: \(F(g) + e^- \rightarrow F^-(g)\)

Step 2: (b) Positive and negative quantities

Now, we will determine which of the two quantities have opposite signs. The first ionization energy is the energy required to remove one electron from an atom, so it's an energy input (positive) process. Therefore, the first ionization energy of Ne will be positive. The electron affinity is the energy released when an electron is added to an atom, so it's an energy output (negative) process. So, the electron affinity of F will be negative.

Step 3: (c) Equality of magnitudes and the larger one

We need to analyze if the magnitudes of these two quantities are equal and, if not, which one is larger. In general, ionization energies are greater than electron affinities. First ionization energy is a result of overcoming the attractive force between the positively charged nucleus and the negatively charged electron. In contrast, electron affinity is defined as the amount of energy released when an electron is added to a neutral atom. Since Neon has a stable electron configuration (full 2p subshell), it's more difficult to remove an electron from it; hence, requiring larger ionization energy. While Fluorine has a strong effective nuclear charge and high electron affinity, it does not have a stable electron configuration. This means that removing an electron from Ne is more difficult compared to adding an electron to F. So, we can conclude that the magnitudes of these quantities are not equal, and the first ionization energy of Ne is expected to be larger than the electron affinity of F.