Question

What is the Lewis dot structure for `S_3^-2`?

Answer 1

`""^(-)S-S-S^(-)`, bent about the central `S`.

Explanation:

The terminal sulfur atoms each bear a negative charge. The central sulfur is neutral. The electron count is 20 electrons, as required (why).

This is a polysulfide anion. You can do this experiment in the lab. You know that sulfur is almost insoluble in water. If you add a bit of sodium sulfide to a slurry of sulfur in water, the sulfur all goes up into solution!

Magic? Unfortunately no, the sulfur comes into solution as rings and chains with formal charges on each end of a chain of variable length.