Basicity of oxoanions
Structural changes which increase acidity decrease basicity.
Thus the basicity of –O– in the oxoanions (O=E–O–) is lower than H–O– due to charge delocalization in the oxoanion.
See below that oxoanions derived from
Thus the basicity of –O– in the oxoanions (O=E–O–) is lower than H–O– due to charge delocalization in the oxoanion.
See below that oxoanions derived from
weak oxoacids (one oxo group) are weak bases
strong oxoacids (two or more oxo groups) are not basic.
strong oxoacids (two or more oxo groups) are not basic.
| weak acids one oxo oxygen at E | |||
 |  |  |  |
| CH3CO2H | H2CO3 | H2SO3 | H3PO4 |
| ethanoic acid | carbonic acid | sulfurous acid | phosphoric acid |
| CH3CO2– | CO32– | SO32– | PO43– |
| ethanoate ion | carbonate ion | sulfite ion | phosphate ion |
 |  |  |  |
| These oxoanions are weak bases | |||
| strong acids two or more oxo oxygens at E | ||
 |  |  |
| HNO3 | H2SO4 | HClO4 |
| nitric acid | sulfuric acid | perchloric acid |
| NO3– | SO42– | ClO4– |
| nitrate ion | sulfate ion | perchlorate ion |
 |  |  |
| These oxoanions are not basic in water | ||