1. Introduction to Chemical Bonding
Bond Formation
Ionic Bonds
Covalent Bonds

2. Chemical Bonds An attractive force that holds atoms together
Formation of chemical bonds involves energy
Bonds will form if atoms have lower energy than when they are separated
Bond formation is (generally) an exothermic process
Bonding deals with valence electrons
Electrons in the highest energy level

3. Lewis Structures
Symbolic representations of elements that show the valence electrons
Elemental symbol and the valence electrons represented by dots

4. Valence Electrons & Noble Gases
Noble gases are unreactive
They don’t form compounds with other elements
Noble Gases already have a stable electron configuration
The highest energy level of the atom is full and it will not form any bonds
Does this always mean there are eight electrons?
No → Helium

5. Valance Electrons and Chemical Properties
The number of valence electrons determines the chemical properties of an atom
Atoms are trying to get to eight valance electrons and they will take the shortest route to get there
“Octet Rule”
Could mean gaining electrons, could mean loosing electrons
“1,2,3,4,5,6,7,8,1,2,3,4…”

6. Ion Formation and the Octet Rule
Atoms will gain or lose electrons to have a full outer shell (valence shell)
Metals lose valence electrons so that the electron configuration becomes like the previous noble gas
Non-metals gain electrons to become like the next noble gas
Exceptions exist for small atoms
Duet Rule

7. How does the bond between sodium & chlorine form?
Sodium has one valence electron. It’s looking to lose it Cl   Na 
Chlorine has seven valence electrons. It’s looking to gain one

8. Ion Formation and the Octet Rule
Main group metals lose all their valence electrons to form cations
This loss of electrons is called oxidation
Non-metals gain electrons to achieve the noble gas configuration and form anions
This gain of electrons is called reduction
“OiL RiG”
Oxidation is loss, Reduction is gain

9. How does the bond between sodium & chlorine form?
Chlorine now has 17 protons & 18 electrons. It has a negative charge. It is an anion
Sodium now has 11 protons & 10 electrons. It has a positive charge. It is a cation Cl   Na

10. Ionic Bond Negative charges are attracted to positive charges
Negative anions are attracted to positive cations
The result is an ionic bond
Ionic Bonds involve the transfer of electrons from a metal to a non-metal

11. How does the bond between sodium & chlorine form?Cl   Na
The negative charge on the chloride ion and the positive charge on sodium ion attract each other and form an ionic bond

12. Structure of an Ionic Solid
Ionic Compounds form a three-dimensional network called a crystal (or crystal lattice)
Each ion is attracted to multiple ions of the opposite charge

13. Properties of Ionic Compounds
High melting point
Don’t easily change to liquids (or gases)
Solids → Poor conductors
Liquids → Good Conductors
Shatters when breaks