---
title: "A student compares the enthalpy changes associated with electron attachment for selected elements in Groups \\(14\\) and \\(15\\). The electron-attachment process is  \\[ \\text{X(g)}+e^-\\rightarrow \\text{X}^-\\text{(g)} \\]  | Element | Ground-state valence configuration | \\(\\Delta H_{\\mathrm{EA}}\\) \\((\\text{kJ mol}^{-1})\\) | |—|—|—| | \\(\\text{C}\\) | \\(2s^2 2p^2\\) | \\(-122\\) | | \\(\\text{N}\\) | \\(2s^2 2p^3\\) | \\(+7\\) | | \\(\\text{Si}\\) | \\(3s^2 3p^2\\) | \\(-134\\) | | \\(\\text{P}\\) | \\(3s^2 3p^3\\) | \\(-72\\) |  A more negative value of \\(\\Delta H_{\\mathrm{EA}}\\) indicates a more thermodynamically favorable electron attachment. Which of the following statements best identifies and explains the discontinuity between the Group \\(14\\) and Group \\(15\\) elements in each period?"
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url: "https://nerd-notes.com/ubq/120025/"
date_modified: "2026-08-21T08:40:24+00:00"
---

# A student compares the enthalpy changes associated with electron attachment for selected elements in Groups \(14\) and \(15\). The electron-attachment process is

\[
\text{X(g)}+e^-\rightarrow \text{X}^-\text{(g)}
\]

| Element | Ground-state valence configuration | \(\Delta H_{\mathrm{EA}}\) \((\text{kJ mol}^{-1})\) |
|—|—|—|
| \(\text{C}\) | \(2s^2 2p^2\) | \(-122\) |
| \(\text{N}\) | \(2s^2 2p^3\) | \(+7\) |
| \(\text{Si}\) | \(3s^2 3p^2\) | \(-134\) |
| \(\text{P}\) | \(3s^2 3p^3\) | \(-72\) |

A more negative value of \(\Delta H_{\mathrm{EA}}\) indicates a more thermodynamically favorable electron attachment. Which of the following statements best identifies and explains the discontinuity between the Group \(14\) and Group \(15\) elements in each period?

A student compares the enthalpy changes associated with electron attachment for selected elements in Groups \(14\) and \(15\). The electron-attachment process is

\[
\text{X(g)}+e^-\rightarrow \text{X}^-\text{(g)}
\]

| Element | Ground-state valence configuration | \(\Delta H_{\mathrm{EA}}\) \((\text{kJ mol}^{-1})\) |
|---|---|---|
| \(\text{C}\) | \(2s^2 2p^2\) | \(-122\) |
| \(\text{N}\) | \(2s^2 2p^3\) | \(+7\) |
| \(\text{Si}\) | \(3s^2 3p^2\) | \(-134\) |
| \(\text{P}\) | \(3s^2 3p^3\) | \(-72\) |

A more negative value of \(\Delta H_{\mathrm{EA}}\) indicates a more thermodynamically favorable electron attachment. Which of the following statements best identifies and explains the discontinuity between the Group \(14\) and Group \(15\) elements in each period?

- **A.** Electron attachment is more favorable for \(\text{N}\) than for \(\text{C}\), and for \(\text{P}\) than for \(\text{Si}\), because the Group \(15\) atoms have greater effective nuclear charge within each period and therefore attract an added electron more strongly.
- **B.** Electron attachment is more favorable for \(\text{N}\) than for \(\text{C}\), and for \(\text{P}\) than for \(\text{Si}\), because the added electron occupies an empty \(p\) orbital in each Group \(15\) atom and produces a half-filled \(p^3\) subshell.
- **C.** Electron attachment is more favorable for \(\text{C}\) than for \(\text{N}\), and for \(\text{Si}\) than for \(\text{P}\), because the added electron enters an unoccupied \(s\) orbital in each Group \(14\) atom and avoids pairing with another electron.
- **D.** Electron attachment is more favorable for \(\text{C}\) than for \(\text{N}\), and for \(\text{Si}\) than for \(\text{P}\), because the added electron completes a half-filled \(p^3\) subshell in each Group \(14\) atom, whereas it must pair with an electron in an occupied \(p\) orbital in each Group \(15\) atom.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120025/*