In the sulfate ion (SO₄²⁻), the oxygen atom that carries a negative charge (O⁻) is involved in resonance. Resonance refers to the delocalization of electrons in a molecule or ion, resulting in the formation of multiple resonance structures that differ in the placement of pi (π) bonds and lone pairs of electrons.
In the sulfate ion, there are several resonance structures that can be drawn. Each of these structures has the same overall arrangement of atoms, but the placement of the double bonds and the location of the negative charge on the oxygen atoms vary. These resonance structures are formed by the movement of pi electrons and lone pairs.
When considering the valence electrons of the O⁻ atom, they can participate in resonance by delocalizing across the molecule. The negative charge can be shared with adjacent oxygen atoms through the movement of pi electrons, leading to the formation of different resonance structures.
Overall, the valence electrons of the O⁻ atom in the sulfate ion can move in resonance structures, allowing for the delocalization of the negative charge and the redistribution of pi bonds and lone pairs among the oxygen atoms.