What is the mass of a single atom of oxygen?

Question

This is a question from my physics homework, I was hoping someone could show me how to do it. 16 grams of Oxygen contains 6.0 X 1023 atoms (Avogadro's number). What is the mass of a single atom of oxygen?

Answer 1

It's about the same as eight protons and eight neutrons; the electrons make very little difference, and the exact isotope of oxygen would determine the actual weight.

But, basically, divide 16.0 grams by Avogadro's Number:

16.0/6.02e23 = 2.6578073089700999e-23

according to Python. That number, 2.66 times 10^-23, is the weight of a single oxygen atom, in grams. That's 2.66e-26 kilograms, incidentally.

Answer 2

Wrong.  

16 g O2 contains 6E23 MOLECULES each having 2 atoms of oxygen

m = 16 g/ (2*6E23) = 1.33E-23 g/atom

Answer 3

Just grab a periodic table and look at it.

15.99

Answer 4

(6 x 10^23 atoms) / (16 grams)