Grams and Moles of an Element

We just learned how to convert between moles and number of atoms, which is like converting between dozens and number of nails. We need one more conversion factor to convert from the mass of a sample to the number of atoms in the sample. For nails, we used the weight of one dozen nails for atoms, we use the mass of one mole of atoms. 

The mass of 1 mol of atoms of an element Is Its molar mass. The value of an element s molar mass In grams per mole Is numerically equal to the element s atomic mass In atomic mass units. 

Recall that Avogadro s number, the number of atoms in a mole, is defined as the number of atoms in exactly 12 g of carbon-12. Since the atomic mass unit is defined as one-twelftii of the mass of a carbon-12 atom, it follows that the molar mass of any element—the mass of 1 mol of atoms in grams of tiiat element— is 

Therefore, the molar mass of any element becomes a conversion factor between grams of that element and moles of that element. For carbon  

58-g diamond would be about a three-carat diamond. 

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