1. Ionic, Covalent and Metallic Bonding
Metallic bonding is a special case of covalent bonding were electrons are shared throughout a crystal. More on Metallic bonding another day.

2. Types of Chemical Bonds
The classification of bonds is based on the extent to which electrons are shared or transferred.

3. C. Bond Polarity
Nonpolar
Polar
Ionic
Link to Dog Video .

4. Link to covalent vs ionic bonds

5. Ionic Bonds
A complete transfer of one or more electrons between two atoms, forming + and – ions.
Ionic bonds are typically formed from a metal and a nonmetal.

7. Ionic Salt Crystal “Lattice ”
Lewis Dot Structure:

8. An equal sharing (“co”) of valence electrons (“valent”).
Covalent Bonds
An equal sharing (“co”) of valence electrons (“valent”).

9. Picture:

10. Polar Covalent Bonds An unequal sharing of valence electrons.
Typically forms between 2 nonmetals.

12. Electronegativity
Defn: The pull an atom exerts on electrons in a chemical bond.
Pauling Scale: Ranges from 0.0 (no attraction) to 4.0 (Highest Attraction)
EN differences are used to predict type of bonds and polarity of bonds.

13. Electronegativity Values

14. C. Bond Polarity Electronegativity Trend
Increases up and to the right.
Largest EN : top right
Why?: small atoms attract e- more strongly than larger atoms
Smallest EN : bottom left

15. C. Bond Polarity
Most bonds are a blend of ionic and covalent characteristics.
Difference in electronegativity determines bond type.

16. Key idea: It is DIFFERENCE in EN that is important, not EN value of an individual atom

17. Using Electronegativity Differences to Determine Bond Type
If EN difference is between
0.0 = covalent bond
0.1 to less than 1.7 = polar covalent
1.7 or above = Ionic

18. Using Electronegativity Differences to Determine Bond Type
Example: CaCl2
1.9 > 1.7 → IONIC:
Example: O2: – 3.5 = 0 → COVALENT
Example: CO2
0.1 to less than 1.7 = POLAR COVALENT

19. + - Polar Covalent Bonds:
The MORE EN atom will be “partial” NEGATIVE and have MORE electron density around it.
Arrow points toward negative side of molecule
Dipole = 2 sides : + side and - side + -
More EN atom = δ-