The electron affinity of sodium is lower than that of lithium, while the electron affinity of ch

step 1 So now problem 110 from chapter 8. In this problem, we're told that the electron affinity of sod

The electron affinity of sodium is lower than that of...

Key Concepts

Electron Configuration and Subshell Structure

The specific arrangement of electrons in an atom’s orbitals—that is, its electron configuration—can influence electron affinity. Atoms with configurations that are either half-filled or nearly complete tend to exhibit extra stability, which can affect the energy change associated with gaining an extra electron. Variations in orbital penetration and subshell energy levels also contribute to deviations from general periodic trends.

Atomic Size and Electron-Electron Repulsion

The size of the atom plays a crucial role in electron affinity. In larger atoms, the incoming electron is added to an orbital that is farther from the nucleus and more shielded by inner electrons, which reduces the effective nuclear charge experienced by the added electron. Additionally, for smaller atoms, high electron density can lead to increased electron-electron repulsions, which might lower the stabilization that would otherwise be provided by adding an electron.

Electron Affinity

Electron affinity refers to the energy change that occurs when an electron is added to an isolated atom in the gaseous state. It is an indicator of the tendency of an atom to gain an electron, and its magnitude can be influenced by factors such as atomic size, nuclear charge, electron-electron repulsions, and the stability of the resulting electron configuration.

Periodic Trends in Electron Affinity

Across the periodic table, electron affinity generally increases across a period and decreases down a group. However, irregularities in this trend can occur because of other factors like electron-electron repulsion and the effectiveness of nuclear charge. These trends help explain why elements in similar groups or periods might have unexpected differences in their affinities for an added electron.

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