So, the mass of one unit of #'NaCl'# is #58.44#'amu'#, and the mass of one mole of #'NaCl'# is #58.44#'grams'#. The atomic masses are not the same as the atomic numbers in the periodic table. By definition, the molar mass of carbon-12 is numerically the same, and is therefore exactly 12 grams. Multiply the subscript (number of atoms) times that elements atomic mass and add the masses of all the elements in the molecule to obtain the molecular mass. We have defined a mole based on the isotopic atomic mass of carbon-12. Unit of Atomic Mass (AMU) One atomic mass unit is equal to 1/12 of the mass of the carbon-12 atom. average of all of the naturally occurring isotopes of that element and atomic mass is the number that appears in the periodic table. The relative mass of an atom is called atomic mass or atomic weight. #overbrace(22.99color(white)(l)'g/mol')^'sodium' + overbrace(35.45color(white)(l)'g/mol')^'chlorine' = overbrace(color(red)(ul(58.44color(white)(l)'g/mol')))^'sodium chloride'#larr ' molar mass'# For this reason, chemists use the relative atomic mass scale instead of atomic masses. This is numerically equivalent to the molar mass of #'NaCl'#.

The atomic mass of #'NaCl'# can be found by using the atomic masses of the individual elements found on a periodic table:

To illustrate this fact, let's look at the compound sodium chloride ( #'NaCl'#). The atomic mass in #'amu'# of a substance is numerically equivalent to the mass in #'g'# of one mole of that substance. The molar mass of a monatomic element is the numerical value listed on the periodic table expressed in units of g/. The molar mass of a substance is the mass per mole of its entities. Molar mass is the mass of one mole of a substance.Ītomic mass is the mass of one individual unit of a substance.Īn important concept regarding the mole is that The periodic table can be used to calculate the molar mass of any substance.

Molar mass on periodic table units