Work Step by Step
In order to find the chemical formula of Aluminum hydroxide, first look at their charges. Aluminum is a metal which has a charge of 3+. Hydroxide $(OH-)$, on the other hand, has a charge of 1-. In order to create a balanced charge, there must be 3 hydroxide molecules for every one Aluminum atom, which has a charge of 3+. Therefore, the chemical formula must be $Al(OH)_3$.