1. Covalent (Molecular) Bonds

2. Covalent (Molecular) Bond Definition
Covalent –“sharing, valence electrons”
Non-metals bonded to non-metals
Bond based on shared electrons between two atoms
Forms a molecule (hence the name)

3. Covalent (Molecular) Bond Properties
Very strong bond, however often not a strong force of attraction between molecules.
As a result molecular compounds have the lowest melting/boiling points

4. Types of Covalent Bonds
Single- one shared pair of e-
Double- two shared pairs of e-
Triple- three shared pairs of e-
Strength: 3>2>1
Q:How do you know what types will form?
A:Use VSEPR!

5. Drawing Covalent Bonds using V.S.E.P.R.
Valence Shell Electron Pair Repulsion
According to VSEPR theory, the repulsion between electron pairs causes molecular shapes to adjust so that the valence-electron pairs stay as far apart as possible.
-Like repels like (+ repels +)(- repels -)

6. VSEPR Steps:
Place either the single element or the C in the middle and arrange the others around it
Draw the Lewis Dot Diagram for each element
Draw a line connecting the valence electrons to represent one pair of electrons until each element fulfills the octet rule

7. Single Bond Example #1 F2
-Group 17 diatomic molecules are single bonds and formed this way!

8. Single Bond Example #2
H2O

9. Single Bond Example #3
CH4

10. Double Bond Example #1
CO2

11. Double Bond Example #2 NO

12. Triple Bond Example #1 N2

13. Triple Bond Example #1
HCN

14. On notebook paper, use VSEPR to draw the following:
Carbon tetrachloride (CCl4)
Ammonia (NH3)
Water (H2O)
Nitrogen (N2)
Hydrogen (H2)
Phosphorous trichloride (PCl3)
Carbon dioxide (CO2)
Ethyne (C2H2)

15. Carbon tetrachloride (CCl4)
Ammonia (NH3)

16. Water (H2O)
Nitrogen (N2) . . . __ . __ __
N N .

17. Hydrogen (H2)
Phosphorous trichloride (PCl3) __
H H

18. Carbon dioxide (CO2)
Ethyne (C2H2)

19.  Drill
Decide whether each substance is composed of covalent or ionic bonds. 1. Methane CH4 2. Carbon Dioxide CO2 3. Potassium Bromide KBr

20. Naming Covalent Bonds

21. Steps to Naming Covalent Bonds
Write name of first element
Use prefix if there’s more than 1
Write name of second element, changing ending to “ide”
Use prefix always

22. Prefixes 1 mono- 2 di- 3 tri- 4 tetra- 5 penta- 6 hexa- 7 hepta-
8 octa-
9 nona-
10 deca-

23. Practice
NCl3
N2H4
CS2
N2O3
Cl2O7
S2F10
Cl4

24. Practice-ANSWERS NCl3 Nitrogen trichloride
N2H4 dinitrogen tetrahydride
CS2 carbon disulfide
N2O3 dinitrogen trioxide
Cl2O7 dichlorine heptoxide
S2F10 disulfur decafluoride
Cl4 tetrachloride