# How does electronegativity affect the strength of an acid?

Another reason is the stability of the ion. For example, HF is an acid, it dissociates in water and gives a proton. In this process, ${F}^{-}$ ion is also formed. But fluoride ion is a very small ion with relatively denser charge which makes it an unstable ion. That's why HF is weaker acid than HCl and HI though it has a greater electronegativity. Hope this picture will help.