periodic table molar mass vs atomic mass

This helps tremendously when having to convert from moles to mass as we often do in chemistry. Because of that old definition, we were able to say that all those atomic weights are in grams per mole of substance or abbreviated g/mol. So why DO we seem to concentrate on the 'gram' as our go to guy on the periodic table for atomic weights and ultimately for molar masses and molecular weights? Well the key here is the way we historically defined the mole. 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. Hint: Count the number of atoms of each element, and then multiply that number by the element's atomic weight.The periodic table can often be presented with an abundance of data about each and every element listed. Use the table below to find the atomic weight of each atom (element), or refer to a Periodic Table of the Elements. Let us calculate the molecular weight of some common compounds. For example, in one mole of a chemical compound there are 6.022 x 1023 molecules. One mole of 'something' contains 6.022 x 1023 entities. A mole is the unit that measures the amount of a substance. One thousand mers connected together would add up to a weight of 28,000 grams/mole and would have 6,000 atoms.Ī mole is the standard method in chemistry for communicating how much of a substance is present. We combine (react) many mers of ethylene together to form a polyethylene chain. The atomic weight of carbon is 12 and that of hydrogen is 1, so one mer of ethylene has a weight of 2(12) + 4(1) = 28.

It has a total of 6 atoms: 2 carbon (C) atoms and 4 hydrogen (H) atoms. The chemical formula for an ethylene monomer is -(CH2-CH2).In order to calculate the molecular weight of one water molecule, we add the contributions from each atom that is, 2(1) + 1(16) = 18 grams/mole.

Using the periodic table of the elements to find atomic weights, we find that hydrogen has an atomic weight of 1, and oxygen's is 16. The chemical formula for water is H2O, which means this molecule has 3 atoms: 2 of hydrogen (H) and 1 oxygen (O) atom.

Periodic table molar mass vs atomic mass