1. What is an atomic mass?
    1. Atomic mass unit (amu)
    1. One atomic mass unit is equal to the mass of one proton
    2. Protons and Neutrons have the almost the same mass
    3. Electrons are too small to count their mass
    4. Atomic mass of an atom is the total mass of the protons and neutrons
    1. Mass number
    1. Total number of protons and neutrons in an atom is called the mass number
    2. You will find the mass number by rounding the atomic mass to the nearest whole number

Ex. Atomic mass of Lithium is 6.941, so the atomic number is 7
    1. Finding Amount of Neutrons

Mass number - atomic number = # of neutrons

Ex. To find the # of neutrons for Lithium:

7 (Mass #) - 3 (Atomic #) = 4 (#of neutrons)