1. Topic: Chemical Bonding
Aim: How are covalent bonds formed, & what are properties of covalent compounds?
Do Now: Explain, in terms of electrons, how an ionic bond forms between magnesium and sulfur
HW:

2. Covalent Bonds Formed when 2 (or more) NONMETALS SHARE e-
Results in a MOLECULE
By sharing, they can use each other’s e- to count towards their octet

3. Characteristics Weaker than ionic bonds
Lower m.p./b.p. than ionic cpds
Can be solid, liquid, or gas at rm. temp.
Soft, Poor conductors, Low mp/bp
SPLash in water (which is covalent)

4. Example: How does H2 form?
The nuclei repel each other, since they both have a positive charge, and like charges repel. + +

5. Example: How does H2 form?
But, the nuclei are attracted to each other’s electrons (each H has 1)
They share the electrons + +

6. Formation of a Covalent Bond

7. Another Example: Covalent Bonding
Fluorine has seven valence electrons F

8. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven F F

9. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons… F F

10. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons… F F

11. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons… F F

12. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons… F F

13. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons… F F

14. F F Covalent bonding …both end with full PELs
Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons…
…both end with full PELs F F

15. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons…
…both end with full PELs F F
8 Valence electrons

16. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons…
…both end with full PELs F F
8 Valence electrons

17. Types of Covalent Bonds
Nonpolar covalent
Polar covalent
Coordinate covalent

18. Nonpolar Covalent Bonds
Same 2 nonmetals bonded
Diatomic Molecules
Br2 I2 N2 Cl2 H2 O2 F2
SHARE THEIR VALENCE e- EQUALLY!

19. Characteristics of Nonpolar Covalent Bonds
Molecules are NOT strongly attracted to one another
They can move freely and tend to exist as liquids or gases at room temperature
Examples?

20. Polar Covalent Bond Ex. CCl4 , H2O, CO2 2 different non metals bonded
THEY SHARE THEIR VALENCE e- UNEQUALLY!
The valence e- are MORE LIKELY TO BE FOUND NEAR THE ATOM WITH THE HIGHER ELECTRONEGATIVITY!
To ID which bond is “more polar”
Find the DIFFERENCE IN ELECTRONEGATIVITY
Bigger difference, more polar bond
Ex: H2O, CO, PCl4

21. Polar Covalent Bond

22. Coordinate Covalent Bond
When 1 atom donates both electrons that are shared
Ex. NH4+
Ex. H3O+
Polyatomic ions (Table E)

23. Network Solids Network solids Form macromolecules
Repeat same structure over and over
Properties: hard, poor conductor, high m.p.
Ex: diamond – no separate particles – carbon atoms connected by covalent bonds to form one big macromolecule
Ex: SiC, SiO2 (silicon dioxide - sand)