1. The Atom 3 major parts of the atom are: Protons Neutron Electrons
Inside the nucleus

2. Protons Located in the center (nucleus)of the atom
It has a positive (+) charge
Mass is 1 AMU (atomic mass unit)
The number of protons defines which element it is
Hydrogen (H) has 1 proton and atomic umber of 1
Carbon (C) has 6 protons and an atomic number of 6
Fluorine (F) has 9 protons and an atomic number of 9 (mass due to protons is 9 AMU)

3. Neutrons Also located in the center (nucleus) of the atom
Charge is neutral (no charge)
Mass of the neutron is 1 AMU
Fluorine (atomic number 9) has a total mass of 19 AMU. 9 comes from protons and 10 (difference) comes from the neutrons
Example:
Ca has an atomic number of 20 and a mass of 40
Total mass is 40 AMU
20 are from protons
20 are from neutrons

4. Electrons Is located outside the nucleus in the “electron cloud”
It has a negative charge
Number of electrons will always equal to number of protons when looking at periodic table
Fluorine has 9 protons (+) and it has 9 electrons (-)
Mass of electrons
Mass of electron is so small, we can simply ignore it

5. The Periodic Table and the atom
The element box
# of protons is 2=# of electrons
Neutrons= mass – protons OR
mass- atomic number