Look up the atomic masses on the periodic table OR look in a table for the elements. An example:
Ca = approximately 40
C = approximately 12
O = approximately 16 and 16 x 3 = 48.
Then add all of them.
40 + 12 + 48 = approximately 100. I just rounded all of them to make it a little easier for you to see.
Here is a table on the web if you don't have one.
Thank you! but what about for a molar mass for a single element? my teacher said it is different from the atomic mass, but all the research i've done says it is not different.
You are right. Atomic masses are the masses you see in the table or on the periodic chart. I suspect your teacher is talking about the molar mass of elements that are diatomic; i.e., two or more atoms to the molecule. For example, O2 is oxygen = 32 (16 x 2)
O3 is ozone = 48 (16 x 3)
N2, F2, Cl2, Br2, I2, H2, are done the same way. P is P4 and S is S8 in the elemental state. I think most, if not all, of the remaining elements are single atoms to the molecule.
I should have said "polyatomic" or "multiatomic" instead of diatomic. N2, I2, H2, and most of the others I listed are diatomic. Of course, you realize O3, ozone, is triatomic, P4 is tetratomic, and S8 is what? Octatomic?