What is the correct formula for Boron and Sulfur?

Question

How do we get B2S3 as the answer. Specifically, trying to figure out how we get 2 and 3..Boron has 3 and Sulfur has 6 electrons in its valence shell.

Answer 1

Boron forms a 3+ ion, sulfur forms a 2- ion to get to the electron configuration of the nearest noble gas. To balance out the charges, there have to be 2 borons and 3 sulfides, hence B2S3.