1. LECTURE 6:
COVALENT COMPOUNDS

2. Binary Covalent Molecules
Contains 2 atoms covalently bonded together
What is a covalent bond?
2 Nonmetals bonded together
Rules:
Do the same as before
Add prefixes

3. Binary Covalent Molecules

4. Naming Covalent Compounds, continued
Section 2 Drawing and Naming Molecules
Chapter 6
Naming Covalent Compounds, continued
Prefixes can be used to show the numbers of each type of atom in diphosphorus pentasulfide.

5. Sample Problems
Name the following covalent compounds CO
CO2
NO2
N2O4

6. Sample Problems Name the following covalent compounds
CO – carbon monoxide
CO2 – carbon dioxide
NO2 – nitrogen dioxide
N2O4 – dinitrogen tetraoxide

7. Writing Binary Formula
Example: Carbon Monoxide
Carbon = C
Monoxide (1 oxide) = O
Formula: CO

8. Naming Compounds Using Numerical Prefixes
Chapter 6
Visual Concepts
Naming Compounds Using Numerical Prefixes

9. CHEMICAL BONDS

10. Chapter 6
Visual Concepts
Chemical Bond

11. Chemical Bond
A mutual attraction between nuclei and valence electrons of different atoms
Only includes “s” and “p” orbitals
This leads us to the ……

12. Types of Bonds Ionic Bonding – e- are transferred
Covalent Bonding – e- are shared
Metallic Bonding – e- are mobile around a large cluster of nuclei

13. Types of Bonds Cation the + charged ion that loses the e- Anion
the – charged ion that gains the e-
Orbitals overlap to create a sharing of e-
e- move freely around the nuclei
Movement creates electricity, malleability, ductility

14. Ionic Bonds Occurs between a metal and a nonmetal
Electronegativity values have a difference >2.1
Metal becomes a cation (+) by giving up 1 or more e-
Nonmetal becomes an anion (-) by taking 1 or more e-

15. Covalent Bonds Occurs between a nonmetal and a nonmetal
Electronegativity values have a difference of < 2.1
Electrons are shared by both atoms

16. Predicting Bond Character from Electronegativity Differences
Chapter 6
Predicting Bond Character from Electronegativity Differences

17. Comparing Polar and Nonpolar Covalent Bonds
Chapter 6
Visual Concepts
Comparing Polar and Nonpolar Covalent Bonds

18. Metallic Bonding Occurs between 2 or more metal atoms
Electrons float around freely creating a negative “sea of electrons” and a positively charged nuclei center

19. Hydrogen Bonding Special Case
Occurs between hydrogen and another element
Typically N, O, or any of the halogens

20. Properties of Substances with Metallic, Ionic, and Covalent Bonds

21. Octet Rule “Eight is great”
Every atom wants a total of 8 valence electrons
2 in the s orbital
6 in the p orbital

22. Drawing Chemical Bonds
LEWIS DOT STRUCTURES
Drawing Chemical Bonds

23. Drawing Lewis Dot Structures Group 1 Write the element symbol
Draw a dot for every valence electron
Dots should be in the form of a box
Group 1
Ends in s1
1 valence electron
1 dot

24. Lewis Electron-Dot Structures, continued
Section 2 Drawing and Naming Molecules
Chapter 6
Lewis Electron-Dot Structures, continued
Lewis Structures Show Valence Electrons
As you go from element to element across a period, you add a dot to each side of the element’s symbol.

25. Lewis Dot Structures Group 2 Group 13 Ends in s2 2 valence electrons
Ends in s2 p1
3 valence electrons
3 dots

26. Lewis Electron-Dot Structures, continued
Section 2 Drawing and Naming Molecules
Chapter 6
Lewis Electron-Dot Structures, continued
Lewis Structures Show Valence Electrons, continued
You do not begin to pair dots until all four sides of the element’s symbol have a dot.

27. Lewis Dot Structures Group 14 – 18 You get the idea
4-8 valence electrons
4-8 dots

28. Lewis Dot Structures for Compounds
Rule 1:
Write the symbol for the element
Rule 2:
Use the group # to determine the # of valence electrons
Rule 3:
Draw the correct # of dots (box) around the symbol

29. Example

30. Sample Problems Draw the Lewis Dot Structure for:
Carbon Tetrachloride CCl4.
Water, H2O.
Carbon Dioxide, CO2.
Nitrogen, N2

31. Comparing Single, Double, and Triple Bonds
Chapter 6
Comparing Single, Double, and Triple Bonds

32. Multiple Bonds
For O2 to make an octet, each atom needs two more electrons. The two atoms share four electrons.
A double bond is a covalent bond in which two atoms share two pairs of electrons.

33. Multiple Bonds, continued
For N2 to make an octet, each atom needs three more electrons. The two atoms share six electrons.
A triple bond is a covalent bond in which two atoms share three pairs of electrons.

34. Chapter 6
Standardized Test Preparation
1. Which of these combinations is likely to have a polar covalent bond?
A. two atoms of similar size
B. two atoms of very different size
C. two atoms with different electronegativities
D. two atoms with the same number of electrons

35. Understanding Concepts
Chapter 6
Standardized Test Preparation
Understanding Concepts
1. Which of these combinations is likely to have a polar covalent bond?
A. two atoms of similar size
B. two atoms of very different size
C. two atoms with different electronegativities
D. two atoms with the same number of electrons

36. 3. How many electrons are shared in a double covalent bond?
Chapter 6
Standardized Test Preparation
Understanding Concepts
3. How many electrons are shared in a double covalent bond?
A. 2
B. 4
C. 6
D. 8

37. 3. How many electrons are shared in a double covalent bond?
Chapter 6
Standardized Test Preparation
Understanding Concepts
3. How many electrons are shared in a double covalent bond?
A. 2
B. 4
C. 6
D. 8