All chemical ratios work just as well with masses as they do with our oh so familiar moles. You can work chemistry mass problems in any mass you want and it will still work because the masses are relative to each other. Not to mention the myriad of masses represented by all the metric prefixes to prepend to "gram". short tons, long tons, drams, grains, or stones. You could think in pounds, or kilograms, or ounces, or even tons, or heaven forbid. Relative masses means that they are all corrected relative to each other. BUT it would be much much better for you to realize that those could be ANY unit of weight/mass you choose and the whole table would still be correct. "Well, I know the weights are in grams because that is how I learned it in high school". Notice how the atomic weights have no units after them. Hey you! LOOK again at any periodic table - including the one above. The diagram below illustrates the parts and their definitions. You need to make sure that you know what each of these parts is and what it represents. You want a lot more periodic tables to chose from? *Note: If you click on the table, you'll launch it into its own window/page on your browser. These three pieces of data are the elemental symbol, the atomic number (typically given the symbol, Z, and the atomic weight. In it's simplest form (shown below), each entry only has three pieces of information that you will need to know. You can also use our molar mass calculator.The periodic table can often be presented with an abundance of data about each and every element listed. Basically, you should know how to find the molar masses of any chemical compound now. Of nitrogen) + (six atoms x 16 grams/mole of oxygen) = 189 grams/mole ofįor all other compounds, the general idea is the same. Will be equal to (1 atom x 65 grams/mole of zinc) + (two atoms x 14 grams/mole The brackets multiplied by the subscript two). Multiplied by the subscript two) and six atoms of oxygen (three atoms in Have one atom of zinc, two atoms of nitrogen (one atom inside the brackets (1 atom x 56 grams/mole Fe) + (2 atoms x 35.5 grams/mole of chlorine) = 127 grams/mole of iron (II) chloride For example, in iron (II) chloride, or FeCl 2, you have one atom of iron and two atoms of chlorine. If you have a subscript in a chemical formula, then you multiply the number of atoms of anything next to that subscript by the number of the subscript.įor most compounds, this is easy. (1 atom x 23 grams/mole Na) + (1 atom x 35.5 grams/mole Cl) = 58.5 grams/mole NaClĢ. If we write this as a calculation, it looks like this: If we have a chemical compound like NaCl, the molar mass will be equal to the molar mass of one atom of sodium plus the molar mass of one atom of chlorine. Molar masses of chemical compounds are equal to the sums of the molar masses of all the atoms in one molecule of that compound. To do this, we need to remember a few rules.ġ. How can I find the molar mass of a chemical compound?įor any chemical compound that's not an element, we need to find the molar mass from the chemical formula. Still, aside from the exceptions above, all elements have the same molar mass as the atomic masses on the periodic table. phosphorus is normally found in clumps of four atoms, P 4, and sulfur is found in clumps of eight atoms, or S 8. That each molecule of the element has two atoms of that element stuck together.Īs a result, the formula of hydrogen is H 2, nitrogen is N 2, etc. In the case of hydrogen, nitrogen, oxygen,įluorine, chlorine, bromine, and iodine, the element is diatomic, meaning In some cases, the element is usually found in a differentįorm than just one unbonded atom. So, in our example, carbon has a molar mass of 12.01 grams per mole. For example, if you want to find the molar mass of carbon, you would find the atomic mass of carbon on the periodic table, and this is equal to the molar mass in grams per mole. The molar mass of elements is found by looking at the atomic mass of the element on the periodic table. How can I find the molar mass of an element? It is also sometimes called: Molecular Mass, Molecular Weight, Formula Mass, or Formula Weight. One atomic mass unit (u) is equal to 1/12 the mass of one atom of carbon-12. Molar mass is the mass (in atomic mass units) of one mole of a of a substance.
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