Problem 55 - Chemistry 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 will 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? Explain your answer.

Step-by-Step Solution

Answer

The ionization energy of neon is positive and has a larger magnitude than the electron affinity of fluorine, which is negative. This is because neon has a very stable electron configuration, making it more difficult to remove an electron, while fluorine has a high electron affinity as it is one electron short of obtaining a stable electron configuration.

Step 1: Write the electron configuration for neon and fluorine

First, we need to write the electron configurations for neon and fluorine. Check the periodic table and find out the atomic numbers of neon and fluorine. The atomic number of neon (Ne) is 10, so its electron configuration is: \(1s^2 2s^2 2p^6\) The atomic number of fluorine (F) is 9, so its electron configuration is: \(1s^2 2s^2 2p^5\)

Step 2: Write the equations for Ionization Energy and Electron Affinity processes

To find the first ionization energy of neon, we are removing one electron from the neutral atom. The equation for this process is: Ne(\(1s^2 2s^2 2p^6\)) → Ne\(^+\)(\(1s^2 2s^2 2p^5\)) + e\(^-\) For the electron affinity of fluorine, we are adding one electron to the neutral atom. The equation for this process is: F(\(1s^2 2s^2 2p^5\)) + e\(^-\) → F\(^-\)(\(1s^2 2s^2 2p^6\))

Step 3: Determine the sign for Ionization Energy and Electron Affinity

When energy is required to remove an electron, the Ionization Energy is positive. When adding an electron the energy is released; hence, the Electron Affinity is negative. Therefore, the ionization energy of neon is positive, while the electron affinity of fluorine is negative.

Step 4: Compare the magnitudes of Ionization Energy and Electron Affinity

We can expect that the magnitude of the ionization energy of neon and the electron affinity of fluorine won't be equal. This is because Neon is a noble gas with a completely filled electron shell (2p subshell is full), which makes it very stable, and it requires more energy to remove one electron from this stable configuration. Conversely, fluorine is one electron short of obtaining a stable electron configuration (2p subshell needs one more electron to become full). So, fluorine has a high electron affinity due to its high effective nuclear charge, which attracts and stabilizes the added electron. However, it will not be the same as the ionization energy of neon. So, the ionization energy of neon has a larger magnitude than the electron affinity of fluorine. In conclusion, the ionization energy of neon is positive and has a larger magnitude than the electron affinity of fluorine, which is negative. The ionization energy is larger because neon's electron configuration is very stable, making it more challenging to remove an electron.