Structure and Bonding Effects on Acid Strength
Binary acids: Ka increases with electronegativity and with size.
For E-H, a higher electronegativity results in a more ionic bond. Larger size gives a more ionic bond.
These factors don’t always work in the same direction.
c increases across a period, Ka increases
c increases up a group, but Ka decreases due to a larger size at the bottom of the group; a more diffuse charge has a lower attraction for H+.