Things that Affect Acidity/ Basicity Chem 343

Charge Effect

atoms with a + FC are more acidic than atoms with no FC. Atoms with no FC are more acidic than atoms with a - FC

Example of Charge Effect

NH4+ is more acidic than NH3

Resonance Effect

Resonance in the conjugate base is a stabilizing phenomenon because it delocalizes the - charge.

Is the H on an aldehyde ever acidic?

NO, NEVER

Hybrid Orbital Effect

H’s attached to sp hybridized atoms tend to be more acidic than H’s attached to sp2 and sp3 atoms of the same element. Lone pairs in sp orbitals tend to be LESS BASIC

Inductive Effect

ONLY based on EN, involves changing the atoms not directly attached to the acidic H

More EN atoms pull electron density away form acidic H and stabilize - charge on conjugate base.

Element Effect

Involves comparing atoms DIRECTLY attached to the acidic H, not solely based on EN, but also on the size of the atom.

Ex- HBr is a stronger base than HCl because Br is bigger than Cl and can better handle the - charge of the conjugate base

EN does also have an effect.