A negatively charged base is more likely to pick up a proton than a neutral. This is because negatively charged species attracts positively charged species more readily than a species without charge. However, a compound with a delocalized negative charge is less basic than one with a localised concentrated charge.
For example, Carboxylic acids are stronger acids than simple alcohols because the negative charge formed once a proton is lost is delocalised over two oxygens in the carboxylate. In the alkoxide formed by the deprotonation of the alcohol, the negative charge is localised on only one oxygen atom. Therefore the carboxylate is a weaker base as the delocalization of the negative charge stabilizes the molecule. Whereas the alkoxide is a stronger base as the localised negative charge, makes it more unstable. Therfore carboxylic acids are stronger acids as the base formed from its deprotonation is more stabilized due to delocalization, than the alkoxide formed by alcohols.
Lone pair accessibility depends on the energy of the lone pair, the higher its energy the stronger the base. The Lone pair can be lowered in energy if it is on a very electronegative element or if it can be delocalised in some manner. The hybridisation of the orbital that the lone pair inhabits, is also very significant. (disscussed further on the next page)
The more stabilised the resultant positive charge is on the conjugate acid, the stronger the base will be. Stabilization can be achieved by delocalization or the solvent which is used. The solvent can stabilise the positive charge by.