* As the atomic masses of the elements in the periodic table increase, the number of atoms in 1mol of each element remains the same.
* If samples of two different elements each represent one mole, then they contain the same number of atoms.
* An Avogardo's constant amount of any element is equivalent to 6.02x10^23 particles.
* The molar mass of an element is the mass of 1mol of the element.
* The atomic mass of Hydrogen is 1.008 amu. The reason that this value is not a whole number is that Hydrogen has more than one isotope.
* A chemical formula includes the symbols of the elements in the compound and subscripts that indicate how many atoms or ions of each type are combined in the simplest unit.
* Changing a subscript in a correctly written chemical formula changes the formula so that it no longer represents that compound.
* A formula that shows the simplest whole-number ratio of the atoms in a compound is the empirical formula.
* The empirical formula is always the accepted formula for ionic compound.
* The empirical formula for a compound shows the symbols of the elements with subscripts indicating the smallest whole-number ratio of the atoms.
* The empirical fomula may not represent the actual composition of a unit of a molecular compound.