ranking most positive to most negative?

Rank the following atoms in order of lowest to highest electron affinity (most negative to most positive):

Cl

F

Br

I

3 Answers

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  • 4 weeks ago

    All of the electron affinities of the four listed halogens are negative (exothermic).

    For Cl, Br and I, the electron affinities become less negative (less exothermic) down the group as the increase in atomic sizes.  In a larger atom, the nucleus holds the incoming electron less tightly and thus it becomes less negative in electron affinity.  Besides, the effect due to the increase in nuclear charge is mostly cancelled by screening effect.

    There is an exception that the electron affinity of F is less negative (less exothermic) than that of Cl.  When an electron is added to an F atom, due to the very small size of the F atom, the electron-electron repulsion between the incoming electron and the electrons in the F atom is much greater than that in the Cl atom.

    Electron affinity from more positive to more negative:

    I > Br > F > Cl

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  • 4 weeks ago

    The electron affinity increases as you move up the periodic table, so the order would be I, Br, Cl, F.

    Careful with referring to them as "most positive to most negative," as their charge is always 0 in their lone state.

  • 4 weeks ago

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