Chemistry Help? Involves finding mols and atoms using torr, L and temp. Need help with part b). I get part a).

Ok so the question is consider 600.mL of N20 at 40C and 400.torr pressure. a) How many gas molecules are present? b) How many atoms are there? I know how to do a) 400 torr= 400mmHg x 1atm/760mmHg=0.526atm and 600.mL=0.6L and 40C + 273.15 kelvin= 313.15 kelvin. Then you use PV=nRT so n= PV/RT = (0.526atm)(0.6L) / (0.082058L)(atm)(mol-1)(kelvin-1)(313.15 kelvin)= (0.526)(0.6) / (0.082058)(313.15)= 0.0123 mol of N20 x 6.022EXP23= 7.40EXP21 molecules. For b) the answer is 2.22EXP22 atoms but I have no idea how to get this answer. Can someone please explain and shows steps as to how to get part b)? Thanks!

You need to convert using Avogadro.
Avogadro's # is 6.022x10^23, the # of atoms or molecules in 1 mol of ANYTHING. It's atoms ONLY if what you are converting is an element. It's molecules if you're converting any type of compound.

Let's check all the math:
PV=nRT
Your conversions are correct, however you don't need to worry about the 0.15 in converting to K (almost no one does -- it's just C+273).
.526(0.6) = n(0.08206)(313)
0.3156 = 25.685n
n = 0.3156/25.685 = 0.0123 mols N2O

a) # gas molecules present?
0.0123mol (6.022x10^23molecules/mol) = 7.41x10^21 molecules (actually I got 7.407, which I rounded up)

b) How many atoms?
How many atoms per molecule? NO2 = 3 atoms
Multiply 3 atoms/molecule (7.41x10^21 molecules) = 2.22x10^22 atoms

Easy. Hope this helps! :)

Well, you arrived at the number of molecules. Since there are 3 atoms per molecule, wouldn't you just multiply by 3?