Here's how to determine the number of valence electrons in the Lewis structure of the sulfate ion (SO₄²⁻):

1. Find the total valence electrons:

* Sulfur (S): Group 16, 6 valence electrons

* Oxygen (O): Group 16, 6 valence electrons each (4 oxygen atoms = 24 valence electrons)

* Charge: The 2- charge means we add 2 more electrons.

Total Valence Electrons: 6 + 24 + 2 = 32 valence electrons

Therefore, the Lewis structure of the sulfate ion (SO₄²⁻) has 32 valence electrons.