acid strength - electron withdrawing vs. electron donating

[505766240]

When it says electron withdrawing or electron donating, are they the same thing? What is the difference and how do you know which term to use?

[tim_villasenor 1k]

I assume they mean electron accepting (withdrawing) or electron donating. These are very different things. Lewis Bases donate electrons and therefore can be described as the latter. Lewis Acids like to accept electrons and are usually in need of them to fill an octect...etc.

[Uma Patil 2A]

I think both terms refer to components of an acid. electron withdrawing components are high in electronegativity, and will give the acid resonance and will have more electron delocalization. delocalization and resonance means that the acid will be more stable, and will therefore be a weaker acid. electron donating components have the opposite effect on the acid as a whole, and will result in a stronger acid.

[Sidharth Paparaju 3B]

Electron withdrawing portions of an acid make an acid stronger (since they would pull e-density away from the O--H bond). Electron donating portions have the opposite effect since they would (in a manner) push electron density, making the O--H bond not as weak, so the acid would not be stronger.