Question

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

Answer 1

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

Explanation:

In `BaCl_2` there is no subscript next to the `"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 `Fe_2(CO_3)_3` the number of iron atoms is two because of the subscript next to it. The number of carbon atoms is 3 `(1 xx 3 = 3)`. 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.