Why does acidity increase with atomic#?

[Coracao]

I am looking for a little clarification on the reason why acidity decreases with electronegativity (in a row). From what I understand the acidity increases with atomic # because the valence electrons are farther away from the nucleus and therefore more willing to give up the proton. So I is more acidic than F,I get that, but O is also more acidic than C? I can see how this makes sense as you increase columns, going down the table because you are increasing in radius, but I cant see the same in a row. Oxygen is more electronegative than C and want to fill its orbitals even more, therefore holding its proton closer. So why is according to this O is more acidic (more willing to give up H)?

Thanks!

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[Rabolisk]

Oxygen still has a filled orbital after it has given up its proton, so that has nothing to do with it. The reason that HF is stronger than H2O, and so forth, is because the F is more electronegative than O, resulting in the electron density being shifted more to the electronegative atom. This makes the H more positive, which makes it easier to abstract.

 

[FranzLO]

We keep talking about electronegativity but the reason why it increases across a row is because the effective nuclear charge is increasing. The higher positive charge allows for a negative charge, formed when giving up a proton, to be more stabilized. Acids can stabilize the charge, while bases want to distribute it more by picking up a proton. I- and Br- are bigger than Cl- and -F so they are able to stabilize the charge better so HI and HBr are therefore more acidic.

 

[SN2ed]

Thread moved. This type of topic belongs in the Study Q&A forum.

 

[Rabolisk]

We keep talking about electronegativity but the reason why it increases across a row is because the effective nuclear charge is increasing. The higher positive charge allows for a negative charge, formed when giving up a proton, to be more stabilized. Acids can stabilize the charge, while bases want to distribute it more by picking up a proton. I- and Br- are bigger than Cl- and -F so they are able to stabilize the charge better so HI and HBr are therefore more acidic.

True, but electronegativity is attributable to effective nuclear charge, so in that sense, they are one and the same.

 

[Coracao]

Oxygen still has a filled orbital after it has given up its proton, so that has nothing to do with it. The reason that HF is stronger than H2O, and so forth, is because the F is more electronegative than O, resulting in the electron density being shifted more to the electronegative atom. This makes the H more positive, which makes it easier to abstract.

Yep that makes sense...thanks