Why is electron affinity positive?

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Discussion Overview

The discussion revolves around the concept of electron affinity, particularly why it is often presented as a positive value despite the expectation that adding an electron to an atom, such as fluorine, would result in a more stable, exothermic reaction. The scope includes theoretical considerations and nomenclature issues in chemistry.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant notes that when an electron is added to fluorine, it achieves noble gas configuration, suggesting that this should lead to a more stable and exothermic reaction.
  • Another participant introduces the idea of "sloppy nomenclature" in chemistry, implying that the terminology used around electron affinity may be misleading.
  • A question is raised regarding the calculation of lattice energy and whether the negative of the given electron affinity value should be used.
  • One participant emphasizes the ambiguity surrounding electron affinity, stating that discussions about it require clarity on the sign convention being used, and also corrects a spelling error in the name of fluorine.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of electron affinity and its sign convention, indicating that multiple competing perspectives remain without a consensus.

Contextual Notes

There is an acknowledgment of the need for clarity regarding sign conventions in the discussion of electron affinity, which may depend on specific definitions and contexts.

Titan97
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I was reading thermodynamics and about Born Haber cycle. There, I found that the values given for electron affinity are positive.
When an electron is added to flourine, it attains noble gas configuration. So i t becomes more stable. So shouldn't the reaction be exothermic?
 
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So while calculating lattice energy, the negative of the given value has to be taken?
 
Electron affinity is especially murky. It makes no sense to talk about it without the sign convention clearly stated. Btw., it's fluorine not flourine.
 
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