1. Starter 3-29 What are the three items that make up an atom?
Atoms join together to form __________?
What is the chemical formula for water?

2. Reading the Periodic Table

3. The Atom

4. Parts Explained
Two items in the Nucleus give us our mass. (Protons and Neutrons).
Electrons and Protons give us the charge of the atom. If protons=electrons, then charge=0.
Electrons are responsible for electricity.

5. Reading the Periodic Table

6. Finding Neutrons Subtract the mass number and the atomic number.
For example: Uranium on the Periodic Table looks like:
To find out how many neutrons a Uranium atom has, subtract 238 and 92.

7. Electrons Usually an atom’s electrons=protons.
If the atom is charged, you will see a superscript with a charge indication. Ex. U+5 or F-, then:
Electrons=protons-charge
SO, for our Uranium Example: electrons=92-(+5)=87
Fluorine electrons= 9-(-1)=10

8. Valence Electrons
If the atom is charged, then the valence electrons will ALMOST ALWAYS=8
If the atom is NOT charged, then the valence electrons are equal to the ones place of the column the atom is in.
For example, carbon is in column 14. It has 4 valence electrons. Chlorine is in column 17, it has 7 valence electrons. Sodium is in column 1, it has 1 valence electron.