# How can the number of atoms of an individual element be determined by usung a chemical formula?

Feb 4, 2018

The subscripts give the number of atoms of a particular atom.

#### Explanation:

In $B a C {l}_{2}$ there is no subscript next to the $\text{Ba}$, so the number of atoms of barium
is 1. There is a subscript of 2 next to the chlorine, so the number of chlorine atoms is 2.

If there is a polyatomic ion, it is necessary to multiply the subscript of the polyatomic ion by the subscript of atoms in the polyatomic ion.

In $F {e}_{2} {\left(C {O}_{3}\right)}_{3}$ the number of iron atoms is two because of the subscript next to it. The number of carbon atoms is 3 $\left(1 \times 3 = 3\right)$. The number of oxygen atoms is 9 (3 xx 3 =9 ).

To find the number of the individual atoms in a molecular formula look at the subscripts and pay attention to the math.