1. Bonding &
Forming Compounds

2. Chemical Bonds
When two atoms move close together, their valence electrons interact.
Atoms want to become stable
Atoms, ions and compounds become stable when they have a full valence shell (also called a “stable octet.”)

3. Types of Bonds There are two main types of bonds: Ionic Bonds:
between cations (+ ions) and anions (- ions) (generally metals and non-metals)
2. Covalent Bonds:
between non-metal atoms

4. Ionic Bonding
The non-metal atom “steals” an e- from the metal atom - +
The non-metal becomes a (-) ion and the metal becomes a (+) ion
Since they are oppositely charged ions, they attract each other and stick together

5. Electrons are transferred from the lithium to the oxygen
e.g.: lithium and oxygen form an ionic bond in the compound Li2O +
Lithium
Oxygen
Electrons are transferred from the lithium to the oxygen 1+ 2- 1+
Li2O has a ratio of 2:1 as shown. Each Li2O has one oxygen ion for every two lithium ions.
Li+
O2-
Li+
Lithium oxide, Li2O

6. Covalent Bonding
In covalent bonding, atoms overlap slightly, and one unpaired electron from each atom will pair together.
A covalent compound is formed when non-metallic atoms share electrons.
A shared pair of electrons is called a “bonding pair.”
A pair of electrons in the valence shell that is not used in bonding is called a “lone pair.”

7. e.g.: Hydrogen and oxygen form a covalent bond in the compound H2O+
Hydrogen
Oxygen
Bonding pair
Lone pair
Each molecule of H2O has exactly one oxygen atom bonded with two hydrogen atoms.

8. Building Compounds Activity
Step 1: Research to find the chemical formula
Step 2: Classify as ionic or covalent
Step 3: Cut and paste the elements to build your compound