Question

How do you calculate atoms of an element?

Answer 1

There are two ways to look at this question
One is the question asking "how do you calculate the atoms of an element within a given compound?"

Let us use water as an example. Examine the chemical formula of water, `H_2O`. The formula tells that the subscript 2 means that there are two hydrogen atoms in one water molecule and one oxygen atom in one water molecule. The subscript is not normally written; it is implied.

The second way to look at this question "How do you calculate the number of atoms of an element in a given number of moles.

A mole is equal to Avogadro's number which is `6.02 x 10^23`
atoms.

If you look at the atomic weight of hydrogen, one mole equals the atomic weight as well. So that means in 1.0 grams of hydrogen, you have `6.02 x 10^23` hydrogen atoms.