How can you determine the number of atoms in a sam- ple of an element?

Question

cuanchi · Answer

Your question is like asking how you can determine how many fruits you have in a bag.
One way is knowing how heavy is the bag with the fruits and then dividing the mass of the total bag by the average weight of one of the fruits. Or you may know how many dozens of the fruit you have in the bag and then multiply that by 12 to know how many fruits do you have.
In your case with the atoms you have to know the amount of the element that you have. This can be in grams or in moles.
If is in grams you have to know the atomic mass of the element, or the name of the element to find the atomic mass. 
If the amount of the element is in moles you just multiply by the Avogadro's number (6.02 x 10^23) that is to mole like 12 is to a dozen.