chemistry
posted by john .
what is the mass in grams?
a) 3.011 x 10^23 atoms F
b)1.50 x 10^23 atoms Mg
c)4.50 x 10^12 atoms Cl
d)8.42 x 10^18 atoms Br
e) 25 atoms w
f) 1 atom Au
can you please explain a and b to me then i'll come back later and see if i did the rest right? Thanks in advance
it needs to be in scientific notation i think.

1 mol of anything contains 6.02 x 10^23 of those anythings; therefore, 1 mol of F atoms will contain 6.02 x 10^23 atoms of F. And it will have a mass of 19.0 grams (Look up the atomic mass of F on the periodic table.) So,
3.011 x 10^23 atoms x (1 mol atoms/6.02 x 10^23 atoms) x (19.0 g F atoms/1 mol F atoms) = ?? grams F. Note how the units cancel to give grams at the end.
b,c,d are done the same way. 
8.42x10^18