Basic qualitative acid/base question

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Discussion Overview

The discussion centers on the question of why acidity increases as one moves down a column in the periodic table. Participants explore various definitions and concepts of acidity, including Bronsted-Lowry, Lewis, and Arrhenius theories, while examining the implications of electronegativity and atomic structure.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions the trend of increasing acidity down a column, suggesting that decreasing electronegativity and increasing proton count should stabilize the E-H bond instead.
  • Another participant provides definitions of acidity, mentioning different concepts such as Bronsted-Lowry, Lewis, and Arrhenius, and notes that the Lewis acidity trend follows electronegativity.
  • The same participant raises the question of whether the discussion pertains to the acidity of cations as one moves down a column, indicating a potential misunderstanding of the original question.
  • There is a suggestion that the stability of dianions may be relevant to the discussion, though it is unclear how this relates to the original question about acidity.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the original question regarding acidity trends, with multiple competing views and interpretations of acidity concepts present in the discussion.

Contextual Notes

There are unresolved assumptions regarding the definitions of acidity being used, as well as the specific context of the question (e.g., whether it refers to neutral elements or cations). The implications of electronegativity and atomic structure on acidity are also not fully explored.

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Homework Statement



Why does acidity increase as you move down a column in the periodic table?


The Attempt at a Solution



It seems to me like the opposite should be true. For one thing, electronegativity is decreasing. And in general it seems like more protons in the nucleus should stabilize an E-H bond.
 
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Must be a trick question...
 
It was a serious question could you explain what you mean?
 
Acidity is the ability to either donate a proton (Bronstead-Lowry type, doesn't apply here except for hydrogen itself) or to accept an electron pair (Lewis concept) or a substance that increases the hydronium ion concentration when dissolved in water (Arrhenius concept). The Arrhenius concept is not applicable if the element does not dissolve appreciably in water.

The Lewis acidity trend follows the electronegativity of the elements which decreases as you move down a column in the periodic table. In addition, the Lewis acidity concept deals with the acceptance of a pair of electrons. If an element were to accept two electrons, it would yield a dianion. Does the stability of dianions increase as you move down a column?
Lewis acidity usually deals with cations rather than the elements.

Were you being asked about the acidity of cations as you move down a column?

Tricksy, tricksy...
 

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