---
title: "The enthalpy changes for the addition of an electron to gaseous fluorine and chlorine atoms are shown in the table below.  | Element | Process | \\(\\Delta H^\\circ\\text{ (kJ/mol)}\\) | | :— | :— | :— | | \\(\\text{F}\\) | \\(\\text{F}(g) + e^- \\rightarrow \\text{F}^-(g)\\) | \\(-328\\) | | \\(\\text{Cl}\\) | \\(\\text{Cl}(g) + e^- \\rightarrow \\text{Cl}^-(g)\\) | \\(-349\\) |  Which of the following statements best explains why the addition of an electron to \\(\\text{F}(g)\\) releases less energy than the addition of an electron to \\(\\text{Cl}(g)\\)?"
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url: "https://nerd-notes.com/ubq/119868/"
date_modified: "2026-08-21T08:16:37+00:00"
---

# The enthalpy changes for the addition of an electron to gaseous fluorine and chlorine atoms are shown in the table below.

| Element | Process | \(\Delta H^\circ\text{ (kJ/mol)}\) |
| :— | :— | :— |
| \(\text{F}\) | \(\text{F}(g) + e^- \rightarrow \text{F}^-(g)\) | \(-328\) |
| \(\text{Cl}\) | \(\text{Cl}(g) + e^- \rightarrow \text{Cl}^-(g)\) | \(-349\) |

Which of the following statements best explains why the addition of an electron to \(\text{F}(g)\) releases less energy than the addition of an electron to \(\text{Cl}(g)\)?

The enthalpy changes for the addition of an electron to gaseous fluorine and chlorine atoms are shown in the table below.

| Element | Process | \(\Delta H^\circ\text{ (kJ/mol)}\) |
| :--- | :--- | :--- |
| \(\text{F}\) | \(\text{F}(g) + e^- \rightarrow \text{F}^-(g)\) | \(-328\) |
| \(\text{Cl}\) | \(\text{Cl}(g) + e^- \rightarrow \text{Cl}^-(g)\) | \(-349\) |

Which of the following statements best explains why the addition of an electron to \(\text{F}(g)\) releases less energy than the addition of an electron to \(\text{Cl}(g)\)?

- **A.** The addition of an electron is less exothermic for \(\text{F}\) because the incoming electron enters a higher energy shell that experiences greater shielding from core electrons.
- **B.** The addition of an electron is less exothermic for \(\text{F}\) because the smaller atomic radius of fluorine results in a weaker coulombic attraction between the nucleus and the incoming electron.
- **C.** The addition of an electron is less exothermic for \(\text{F}\) because the incoming electron enters the relatively small \(2p\) subshell, where strong electron-electron repulsions partially offset the nuclear attraction.
- **D.** The addition of an electron is less exothermic for \(\text{F}\) because the fluorine atom has a lower effective nuclear charge than the chlorine atom.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119868/*