1. How many atoms combined to form these two water molecules?
Combinations of Atoms
UNIT 2 - Lesson 3 Notes
How many atoms combined to form these two water molecules?

2. Combinations of Atoms Carbon Oxygen Hydrogen
When atoms of more than one element combine, they form a compound.
Carbon
Oxygen
Hydrogen

3. BONDS
Bond – the force that holds atoms in compounds together.
Hydrogen Bond

4. Bonds and Electrons
Bonds are caused by the electrons. The atoms want their outer shell to be filled.
First shell holds 2
Outer shell holds 8

5. Covalent Bonds
Covalent bonds form by sharing electrons that fill the valance shell.
Here's Covalent Bond Bear!
Move Over Share Bear!
The PINK electrons are the ones that are SHARED.

6. How do we get charged atoms? Fluorine now has a negative charge. F -
Ionic Bonds
Valenece Shell is not FILLED.
Fluorine is not happy!
Ionic bonds combine if atoms became positively or negatively charged.
How do we get charged atoms?
P E + - + - + - + - + -
Protons (+)
Neutrons (0)
Electrons (-)
Fluorine now has a negative charge. F - + - + - + - + - -

7. Na+ Cl - Ionic Bonds Electrically charged atoms are called ions.
Ions are attracted to each other when they have opposite charges.
Na+
Cl -

8. Find the charges of the following examples:- - - + + - + - + + - - - + + - + + + + + + +1 -2 +2 + + -