Clearly, there are N_Axx0.400 N_2O_5 molecules in such a molar quantity. Here we use N_A, "Avogadro's number", just as we would use any other collective number, like a "dozen", or a "score", or a "gross".
And so there are 0.400*molxx6.022xx10^23*mol^-1, approx. 2.40xx10^23 individual N_2O_5 molecules. What is the mass of this molar quantity?
And as regard to "atoms" there are 0.400*molxx7*"atoms"*mol^-1 = 2.8xxN_A atoms.
The Lewis structure of N_2O_5 is non-trivial, and charge separation with quaternized nitrogen occurs to give: ""^(-)O(O=)N^(+)-O-^(+)N(=O)O^-. What is the overall charge on this molecular representation?
