1. Ionic and Covalent bonding Chapters 15 and 16

2. Lewis Dot Diagrams
Ex) Draw the Lewis Dot diagram for oxygen (atomic #8)
step # 1) determine the number of valence electrons (electrons in outer level)
Oxygen is in group 6 A
oxygen has 6 valence electrons
Step # 2) Draw dot structure
. . . O : .

3. Si . . . . Ex) Draw a Lewis Dot diagram for silicon (atomic #14).
step #1 determine valence electrons
Silicon is in group 4A
silicon has 4 valence electrons
step # 2) Draw dot structure . . . Si .

4. Octet Rule: atoms having 8 electrons in their outer level have the highest degree of stability.
- electrons can be transferred (ionic bond) or shared (covalent bond) for the atom to achieve a total of eight electrons
- the Noble Gases already have eight electrons which is why they are unreactive.

5. Br K K+ + Br - KBr . . . . : . . Ex) potassium & bromine
Ionic Bond - electrostatic force that holds two atoms together due to a difference in charge
-electrons are transferred usually from a metal to a nonmetal
Ex) potassium & bromine
e- transferred
. . . o Br K . :
. .
K+ +
Br -
KBr

6. Ex) Use Lewis dot diagrams to determine the formula of calcium fluoride.
. . o F . : .
. . Ca .
2e- transferred
. . F o . :
. .
Ca+2
+ 2 F -
CaF2

7. Properties of Ionic Compounds
- are solid, generally forming crystals
- have high melting points (because their bonds are so strong)
- conduct electricity in the molten state and
when dissolved in water
Metallic Bond - chemical bond that occurs
between pure metals
- electrons are free to drift from atom to atom
- positive charge on nucleus pulls any
electron toward it, even if it is from a different atom

8. Covalent Bond - attractive force between two atoms that share electrons to form molecular cmpds.
Ex) H2O H H x . . x . H . O : O : x
. .
. . H x

9. Types of Covalent Bonds
I) Single bond:
one pair of electrons are shared
Ex) Cl2
. .
. .
. .
. . . . Cl Cl Cl x Cl : : : : x
. .
. .
. .
. . Cl Cl
structural formula:

10. . . C C . . C C H H H H H H H H II) Double bond :
two pairs of electrons are shared
(4 electrons total) . H H . x
Ex) C2H4 (ethene) x C C x x . . x x x x H H H H C C
structural formula H H

11. . . C C C C H H H H III) Triple bond :
three pairs of electrons are shared
(6 electrons total) . .
Ex) C2H2 (ethyne) C C H x x x H x x x x x C C H H
structural formula

12. Examples of covalent bonds. . H H H H
1) H2
. .
. . . .
2) O2 . . O O O O
. .
. . . . . . O . O .
3) H2O . . H H H H

13. . . . .
4) NH3 . . . . H N H H N H . . H H . . . . . . . . . . C . . . O O .
5) CO2 . . O C O

14. coordinatecovalent bond
IV) Coordinate Covalent bond:
one atom contributes all of the electrons
to that bond.
coordinatecovalent bond . .
Ex) SO2 . S . . . . x . . . x O . . O . . . .

15. O O O O O O or V) Resonant bond:
bond will resonate between different locations
. .
Ex) O3
. .
. . . O O O .
. .
. . or
. .
. .
. . . O O O .
. .
. .

16. DEN = 0.0 - 0.4 DEN = 0.4 - 2.0 DEN > 2.0 covalent ionic
polar covalent
ionic

17. H H O O H H . . : . . d+ d+ d- VII) Polar bond: (polar covalent)
- unequal sharing of electrons
- one atom holds electrons more tightly due to greater electronegativity
- creates a partial positive & partial negative charge on the molecule H d+ H . x O . O : x H H
. . d+ d-

18. O H H H O H O H H .... Hydrogen bond:
-partial charge on a hydrogen atom bonds to partial charge on another atom
- has about 5% of the strength of a covalent bond d- O d+ d+ d+ H H H
.... O H O d- H d- d+ d+ H d+