# How much does 1.00 mole of SiO_2 substances weigh in grams?

Well what is the mass of a mole of oxygen atoms? It is $16 \cdot g$...
And what is the mass of a mole of silicon atoms? It is $28.1 \cdot g$..
And thus $S i {O}_{2}$ has a molar mass of $\left(28.1 + 2 \times 16.0\right) \cdot g \cdot m o {l}^{-} 1$. From where did I get these molar masses?