How many helium atoms are in 12 grams of helium?

To determine the number of helium atoms in 12 grams of helium, we should use Avogadro's number and the atomic mass of helium.

Step 1: Find the molar mass of helium. Helium has an atomic mass of approximately 4 grams/mol.

Step 2: Calculate the number of moles of helium in 12 grams. Number of moles = mass of helium / molar mass of helium Number of moles = 12 grams / 4 grams/mol Number of moles = 3 moles

Step 3: Use Avogadro's number to find the number of atoms in 3 moles of helium, since Avogadro's number is 6.022 x 10^23 atoms/mol, which is the number of atoms in one mole of any substance. Atoms of helium = number of moles x Avogadro's number Atoms of helium = 3 moles x 6.022 x 10^23 atoms/mol

Step 4: Perform the multiplication to get the total number of atoms. Atoms of helium = 3 x 6.022 x 10^23 Atoms of helium = 18.066 x 10^23 Atoms of helium = 1.8066 x 10^24 atoms

So, there are approximately 1.8066 x 10^24 helium atoms in 12 grams of helium.