* Oxygen's Oxidation Number: Oxygen usually has an oxidation number of -2, except in peroxides.
* Overall Charge: The overall charge of a neutral compound is zero.
* Setting up the Equation: Let 'x' be the oxidation number of bismuth. We have two bismuth atoms and three oxygen atoms:
2(x) + 3(-2) = 0
* Solving for x:
2x - 6 = 0
2x = 6
x = +3
Therefore, the oxidation number of bismuth in Bi₂O₃ is +3.
