First, you must find the number of moles of copper that your sample has. This is calculated by #of moles= your sample mass (in grams)/ atomic mass (in grams) #of moles=68.7g/63.546g #of moles= 1.08 moles present
Then to find the number of atoms present, we must multiply the number of moles present in the sample with Avogadro's number, which is 6.022x10^23 (this number is the number of atoms present in each mole) # of atoms present in copper sample=1.08(6.022x10^23) #of atoms present in copper sample= 6.50x10^23
