General Chemistry - Lesson 8: Molar Mass, Formula Mass, Molecular Mass

Atomic Mass

Average mass of atoms in an element

Atomic Mass Unit

amu

Molecules

Combination of different atoms to form compounds, particle unit of covalent compounds

Isotopes

Atoms with same atomic number but different atomic mass and percent abundance

Percent abundance

How abundant an element is in the environment

Formula Units

Present in ionic compounds

Covalent Compounds

Compounds formed by combined atoms by sharing electrons

Ionic Compounds

Compounds formed by transfer of electrons, can be cations or anions

Mole

Term used to refer to quantity of particles of a substance

Formula Mass

Sum of atomic weight of atoms in empirical formula (cannot be simplified), simplest positive integer ratio (ex: C4H5O, simplest form)

Molecular Mass

Average mass in a molecular formula, gives total number of atoms of a substance (ex: (C5H4O)3 can be simplified)

First step to find formula/molecular mass

Determine the chemical formula

Second step to find formula/molecular mass

Determine the number of atoms of each element

Third step to find formula/molecular mass

Use the periodic table to determine atomic mass

Fourth step to find formula/molecular mass

Multiply the number of atoms of each element with the atomic mass

Fifth step to find formula/molecular mass

Add up all the values to get the formula/molecular mass