1. 4.1 Types of Chemical Bonds

2. Lewis Theory of Bonding
Atoms and ions are stable if they have a full valence shell of electrons (noble gas configuration)
Electrons are most stable when they are paired
Atoms form chemical bonds to achieve a full valence shell of electrons. This may be achieved in two ways:
An exchange of electrons between metal and non-metal atoms
Sharing of electrons between non-metal atoms

3. Lewis Diagrams A simplified version of a Bohr-Rutherford diagram
The chemical symbol represents the nucleus and core electrons
Dots around the symbol represent the valence electrons

4. Ionic Bonding
An ionic bond is the electrostatic attraction between oppositely charged ions
Ionic bonds are found in ionic compounds (ex: NaCl, Al2O3, etc. )
Ionic bonds involve electron transfer (one atom loses electrons and another atom gains them)
An ionic bond usually occurs between a metal and a non-metal
Atoms held together by ionic bonds usually have a very high difference in electronegativity

5. Ionic Bonding

6. Crystal Lattice Structure
In an ionic compound, ions will arrange themselves in a crystal lattice to maximize attractions between opposite charges and minimize repulsions between like charges

7. Covalent Bonding
A covalent bond is a chemical bond in which atoms share bonding electrons
Covalent bonds are found in molecular elements (ex: H2, Cl2, O3) and molecular compounds (H2O, CO2, C3H8)
A covalent bond usually occurs between two non-metals
There are two types of covalent bonds:
Non-polar covalent
Polar covalent

8. Covalent Bonding

9. The Octet Rule
Atoms tend to gain, lose, or share electrons until they are isoelectronic with a noble gas (have the same number of electrons as a noble gas)
The octet rule is the observation that many atoms tend to form the most stable substances when they are surrounded by eight electrons in their valence shell
NOTE: Hydrogen is an exception. It follows the duet rule where it shares only one electron to reach an outer shell of two electrons

10. Lewis Structure
A Lewis Structure is a diagram that shows the arrangement of electrons and covalent bonds in a molecule or polyatomic ion

11. Steps for Drawing Lewis Structures
Pg. 197

12. Practice
Draw the Lewis structure for
Sulfur trioxide chlorate ion

13. Exceptions to the Octet Rule
Hydrogen always obeys the duet rule
Carbon, Nitrogen, Oxygen, and Halogens often obey the octet rule
In all other atoms you may see exceptions to the octet rule
Underfilled Octets Overfilled Octets
Ex: Boron trifluoride Ex: Sulfur hexafluoride

14. Practice
Draw the Lewis structure for BrF5

15. Coordinate Covalent Bonding
A coordinate covalent bond is a covalent bond in which the electrons involved in bonding are from one atom

16. Homework Required Reading: p. 192-205 Questions: P.200 #1-2 P.204 #1-2
(remember to supplement your notes!)
Questions:
P.200 #1-2
P.204 #1-2
p.205 #1-7