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Ch.7 - Periodic Properties of the Elements
Chapter 7, Problem 50

If the electron affinity for an element is a negative number,does it mean that the anion of the element is more stablethan the neutral atom? Explain.

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Understand the concept of electron affinity: Electron affinity is the energy change that occurs when an electron is added to a neutral atom in the gaseous state to form an anion.
Recognize that a negative electron affinity value indicates that energy is released when an electron is added to the atom, suggesting that the process is exothermic.
Consider the stability of the anion: A negative electron affinity implies that the anion is more stable than the neutral atom because the system releases energy, which is generally associated with increased stability.
Compare the stability of the anion and the neutral atom: Since energy is released when forming the anion, it suggests that the anion is at a lower energy state compared to the neutral atom, indicating greater stability.
Conclude that a negative electron affinity value typically means that the anion is more stable than the neutral atom, as the formation of the anion is energetically favorable.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Electron Affinity

Electron affinity is the amount of energy released when an electron is added to a neutral atom to form a negative ion (anion). A negative electron affinity indicates that energy is required to add an electron, suggesting that the process is not energetically favorable. This concept is crucial for understanding the stability of anions relative to their neutral atoms.
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Stability of Anions

The stability of an anion refers to its tendency to remain in that charged state without reverting to the neutral atom. If an anion is more stable than the neutral atom, it means that the anion is energetically favorable and less likely to lose its extra electron. This stability is influenced by factors such as electron-electron repulsion and the effective nuclear charge experienced by the added electron.
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Energetics of Ion Formation

The energetics of ion formation involves the balance between the energy required to add an electron and the energy released when the anion forms. If the process of forming an anion is endothermic (requires energy), the anion is less stable than the neutral atom. Conversely, if the process is exothermic (releases energy), the anion is more stable, highlighting the importance of understanding these energy changes in assessing ion stability.
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