Go to Insert tab find Symbols group and click Equation button. Click anywhere outside of the box to finish. Use the equation feature designed for math but works okay for chemistry.
You can click Write button and use your mouse or writing pad to write the formula here.
Select the equation you want to add. Use the symbols templates or frameworks on the Equation toolbar to edit the equation. Microsoft word shortcut for inserting division sign using Math Autocorrect For typing division sign use instead of. On the ribbon go to InsertEquation.