# How do you find the ionic or covalent chemical formulas for molecules?

## For example: Sulfur trioxide Carbon tetrachloride Silicon dioxide

We write $S {O}_{3} ,$ $C {\left(C l\right)}_{4} ,$ and $S i {O}_{2}$ very easily. We forget the experiments that chemist performed 150-200 years ago to establish these compositions and formulae.