How do I find the molar mass of the elements on the periodic table?
Finding the molar mass of elements sounds pretty daunting . . . but it's not! In fact, if you've taken a look at the periodic table before (and I think it's safe to assume you have, if you've set foot in a chemistry class), you've seen the molar mass of most elements. Let me explain:
The molar mass of an element is the mass in grams of one mole (6.02 x 1023 particles) of the element. So in most cases, to find the molar mass of an element, you just need to look at its atomic mass (atomic weight) on the periodic table. Remember — that's the number written under the element symbol and element name. For example, take a look at carbon and you'll see it has an atomic mass of 12.01. So the molar mass of carbon is 12.01 grams per mole. Pretty easy, huh?
Now comes the tricky part. Did you notice that I said this method works in most cases? The exceptions to this rule are those elements that are usually found in a different form than just one unbonded atom. Seven elements (H, N, O, F, Cl, Br, and I) are diatomic; as pure elements, they form molecules containing two atoms. To find the molar mass of a diatomic element, you need to multiply its atomic weight by two.
Then there are the few elements that are found in molecules of more than two atoms. Phosphorus usually contains four atoms, while sulfur and selenium normally consist of eight atoms.
But aside from the exceptions, find the element's atomic weight and you've got its molar mass.