One atom of copper has a mass of
One gram of copper contains
The be able to determine the mass of an individual copper atom, you need to use copper's molar mass.
Copper's molar mass expresses the mass of 1 mole of copper atoms. One mole of any substance contains exactly
In your case, 1 mole of copper will contain
In other words,
In order to get how many copper atoms are in one gram of copper, you can write