What is the mass of 3.0 x 10^23 atoms of neon

3.0e23 atoms Ne

"E" means 10^

Then we multiply it by a mole of Ne. By the definetion of a mole, it is always 6.022e23 atoms of an element.

So now, we do this:

3.0e23 atoms Ne x (1 mol Ne / 6.022e23 atoms Ne)

After that, we use molar mass. A mole of Neon is equal, in terms of grams, to its avg. atomic mass. This goes true for any element.

It ends up like this:

3.0e23 atoms Ne x (1 mol Ne / 6.022e23 atoms Ne) x (20.1797 g Ne / 1 mol Ne)

Now cancel out the "atoms Ne" and "1 mol Ne"

You end up with a grand total of...
*plugs everything into a calculator*

10.05298... g Ne.

We need to round to 2 sig. figs. (3.0) so now it's

10 g Ne.

Note that this method can only be used for converting atoms of an element to mass in grams.
Source(s):
A periodic table for the atomic mass of neon.
A chemistry textboook
A chemistry class.