Question

the photoelectron spectra above show the energy required to remove a 1s electron from a nitrogen atom and from an oxygen atom. which of the following statements best accounts for the peak in the upper spectrum being to the right of the peak in the lower spectrum?
a nitrogen atoms have a half - filled p subshell.
b there are more electron - electron repulsions in oxygen atoms than in nitrogen atoms.
c electrons in the p subshell of oxygen atoms provide more shielding than electrons in the p subshell of nitrogen atoms.
d nitrogen atoms have a smaller nuclear charge than oxygen atoms.

Explanation:

• Option A: The half - filled \(p\) subshell in nitrogen is related to its valence electrons' stability, not the \(1s\) electron binding energy.
• Option B: Electron - electron repulsions in the valence shell (e.g., \(2p\) for \(O\) and \(N\)) do not directly affect the \(1s\) electron binding energy.
• Option C: Shielding by \(p\) subshell electrons is mainly relevant for outer - shell electrons, not the \(1s\) core electrons.
• Option D: The binding energy of a \(1s\) electron depends on the nuclear charge. Oxygen (\(Z = 8\)) has a larger nuclear charge than nitrogen (\(Z=7\)). According to Coulomb's law (\(F=\frac{kq_1q_2}{r^{2}}\), where \(q_1\) is the nuclear charge and \(q_2\) is the electron charge), the greater the nuclear charge (\(Z\)), the stronger the attraction for the \(1s\) electron. A stronger attraction means a higher binding energy (binding energy is the energy required to remove the electron). Since the peak (representing \(1s\) electron binding energy) for \(O\) is to the right (higher binding energy) of \(N\)'s peak, and \(N\) has a smaller \(Z\) than \(O\), this option is correct.

Answer:

D. Nitrogen atoms have a smaller nuclear charge than oxygen atoms.