Atoms to grams?

Question

1.2 x 10^4 atoms of Si to grams?

Answer 1

(1.2 x10^4) / (6.022 x10^23) = 1.993 x10^-20 mols
atoms ^ - - - - - 1 mol ^

(1.993 x 10^-20 mols) x (28.086 grams) = 5.597 x 10^-19 grams of Silicon

Answer 2

1 mole of atoms is one atomic weight of atoms in grams.

So, 6.0221415 × 10^23 atoms of Si = 28.0855 grams because the atomic weight of Si = 28.0855.

You are looking for grams of Si per 1.2 x 10^4 atoms

1.2 x 10^4 atoms * (28.0855 grams / 6.0221415 × 10^23 atoms) =
5.60 x 10^-19 grams