1. Chemical Bonding

2. Bonding Bonding is the combining of elements to form new substances.
During bonding the first energy level can hold a maximum of 2 electrons and the second and third energy level can each hold 8 electrons.
Bonding involves the incomplete outermost energy level of an atom and the valence electrons.

3. Compounds
Atoms form compounds by combining their outer ring (valence) electrons.
A total of 8 valence electrons are needed to form a bond.
An atom will bond with another atom if doing so gives both atoms a total of 8 valence electrons.
A chemical equation is an expression in which symbols and formulas are used to represent a chemical reaction.

4. Symbols are 1 or 2 letter representations of elements from the periodic table. (Ex. C for carbon or H for hydrogen)
Formulas represent a combining of symbols to form a compound. (Ex. NaCl for salt)

5. Types of Bonds
There are 2 different types of bonds, ionic and covalent.
Ionic bonding involves a transfer of electrons and the formation of ions.
An ion is a charged particle, either positive or negative.
A positive ion is formed when an atom loses an electron.
A negative ion is formed when an atom gains an electron.

6. The ions in an ionic bond are held together because of their opposite charges. They attract like magnets.
Covalent bonding involves the sharing of electrons between atoms.
During covalent bonding ions do NOT form.

7. Periodic Table Review
Elements to the left of the zig-zag line are metals.
Elements to the right of the zig-zag line are non-metals.
The number of valence electrons in an atom is related to the group number.
A single digit group number is the number of valence electrons and if there is a double digit group number the second digit is the number of valence electrons.

8. Atoms of most metals have less than 4 valence electrons.
Atoms of most non-metals have more than 4 valence electrons.

9. Rules for Bonding Metals lose electrons during bonding.
Non-metals gain electrons during bonding.
Atoms will bond together if it completes their outermost energy level with 8 electrons.
Ex: An atom with 2 valence electrons will bond with an atom with 6 valence electrons because it will complete the energy level.

10. You can use more than 1 of each atom to complete the outermost energy level.
Ex. An atom with 6 valence electrons can bond with TWO atoms that have 1 valence electron each because this still completes the outermost energy levels.
The formula for the compound is taken from how many atoms of each atom are used during this process.
Ex: Hydrogen has 1 ve and Oxygen has 6 ve. If you combine 1 oxygen with 2 hydrogens It completes the outermost energy level. Formula = H2O

11. Valence Charges
1. If an atom loses electrons it will get one positive charge for each electron lost. (Ex. When calcium loses 2 electrons it becomes Ca2+)
2. If an atom gains electrons it will get one negative charge for each electron gained. (Ex: When sulfur gains 2 electrons it becomes S2-)