Calculating formula mass, empirical formula and molecular formula

Atomic Mass (amu)

Also known as mass number. Sum of protons and neutrons of a single atom.

Atomic Weight (amu)

weighted average of the atomic mass of all natural isotopes of an element.

Formula Mass

used for compounds that are made up of ions and have primarily ionic bonding.

sum of all atomic weight of the atoms that make up the compound.

Molecular Mass

used for compounds that are made up of molecules and have primarily covalent bonding.

sum of all atomic weight of the atoms that make up the compound.

Molar Mass

mass (g)of a given substance divided by the amount (mole) of that substance.

equivalent

Atomic weight is ____ to molar mass.

Empirical formula

the lowest whole-number ratio of the elements in a compound.

Molecular (Chemical) Formula

The actual composition of a compound indicating the number of atoms per element or the number of moles of each kind of atom per mole of compound.

molecular

Sometimes the empirical formula of a compound is its _____ formula as well.

Percent composition

This is the percent by mass of each element in a compound.