1. Catalyst – February (72-46)/2, 2011 WAY BACK WEDNESDAY! HW OUT!
What is the mass of an atom that has 14 protons and 15 neutrons?
The reaction of baking soda and vinegar at 25 degrees Celsius produces gaseous carbon dioxide for 1 minute. Which of the following do you think will happen if you react baking soda and vinegar at 50 degrees Cesius?
a) Less gas will be produced
b) Gas will be produced for more than 1 minute
c) The reaction will have a strong odor
d) The reaction will not occur

2. Today’s Agenda Catalyst Review Naming and Formulas
Electronegativity Difference, Bond Type, and Bond Polarity
Review = Time to WORK
Exit Question

3. Today’s Objectives
SWBAT name ionic and covalent compounds using CORRECT rules.
SWBAT determine bond type (ionic or covalent) using electronegativity differences (∆EN).
SWBAT get ready to DOMINATE both phases of the Unit 3 Test!

4. REVIEW OF
NAMING &
FORMULAS!

5. Yo Yo! Let’s break it down!
IONIC
Metal + Nonmetal
Writing Formulas:
Kriss Kross charges
Naming:
2nd element ends in – ide, ignore subscripts
COVALENT
Nonmetal + Nonmetal
Writing Formulas:
Prefixes = subscript #s
Naming:
Use prefixes, 2nd element ends in -ide

6. How do we know if this is a covalent compound?
Is it between a metal and a non-metal?
YES!!! Then, it is ionic!!!
Is it between a non-metal and a non- metal?
YES!!! Then, it is covalent!

7. Naming Ionic Compounds
A compound made from Lithium and Oxygen
How do we know if it is ionic or covalent?
Metals and non-metals make ionic compounds

8. Ionic Bond
Cation: Li
Anion: O
Li O

9. Ionic Bond
Cation: Li
Anion: O
Li+ O2-

10. Ionic Bond
Cation: Li
Anion: O
Li+ O2-

11. Ionic Bond
Cation: Li
Anion: O
Li2O

12. MgO

13. Naming Ionic Compounds
MgO
Magnesium Oxide

14. NBr3

15. Naming Covalent Compounds
NBr3
Nitrogen tribromide

16. Write the names and formulas… First! Decide if it’s ionic or covalent!
Write names
Na2O
CO2
CaBr
Na2CO3
Mg3P2
K2S
N2S3
Write formulas
Carbon monoxide
Barium nitrate
Xenon difluoride
Carbon tetrachloride
Sodium carbonate
Lithium fluoride
Nitrogen trifluoride

17. How to tell ionic and covalent apart
We can look at the formula:
Ask yourself: Is it a metal and nonmetal or nonmetal and nonmetal?
Key Point #1: Along with looking at the formula, we can also look at electronegativity differences (∆EN) in to determine bond type (ionic or covalent).

18. Electronegativity Differences
We can also look at electronegativity differences (∆EN)
Look at Electronegativity Chart to find element electronegativities
Find the difference by using subtraction
Look at Bond Type Chart to determine bond types
Electronegativity Chart

19. Remember…
Electronegativity is an atom’s ability to attract electrons to itself in a chemical bond
Electronegativity is expressed in numerical values of 4.0 or less
These numerical values are called Paulings
Higher number means the atom will attract electrons more strongly

20. Electronegativity Chart
Pauling Values

21. Bond Polarity
Key Point #2: Bond polarity is based on differences in electronegativities of atoms forming a bond
As electronegativity difference (∆EN) increases, polarity of bond increases

22. Bond Polarity Terms to Know
Pure Ionic = Complete transfer of electrons from one atom to another
Polar Covalent = Unequal sharing of electrons between two atoms
Nonpolar Covalent = Equal sharing of electrons between two atoms

23. Pure Ionic Bonding I have no chance!
Total give and take (transfer) of electrons! = Big ∆EN!
I have no chance!

24. Covalent Bonding is like a Tug-of-War
The more electronegative atom will pull electrons harder

25. Polarity and Electronegativity
Polar Covalent - electrons are pulled more toward one of the atoms
Big ∆EN!
Nonpolar Covalent - electrons are shared equally between atoms
Low ∆EN!
Big Dog – Little Dog
Medium Dog – Medium Dog

26. Polarity Ranges
Key Point #3: Bonds are not purely ionic (I) or purely covalent (NPC). They could be slightly ionic (VPC) or slightly covalent (MPC).

27. How to Calculate Electronegativity Difference (∆EN)
1. Using Electronegativity Chart, find Pauling values for each element
2. Subtract the smaller number from the bigger number
Example: 4.0 (F) – 0.9 (Na) = 3.1
3. Look at Bond Type Chart to determine bond polarity

28. Bond Type Chart – Copy into notes!
DEN Range
Bond Type
0.0 – 0.39
Nonpolar Covalent
0.4 – 0.89
Moderately Polar Covalent
0.9 – 1.69
Very Polar Covalent
1.7 or greater
Ionic

29. Example 1 Determine the type of bond in LiBr
Find electronegativity of each atom

30. Electronegativity Chart

31. Example 1 Determine the type of bond in LiBr
Find electronegativity of each atom
Li = 1.0 Paulings, Br = 3.0 Paulings

32. Example 1 Determine the type of bond in LiBr
Find electronegativity of each atom
Li = 1.0 Paulings, Br = 3.0 Paulings
Find Electronegativity Difference (∆EN)
DEN = 3.0 – 1.0 = 2.0
Look at chart to determine bond type.

33. Moderately Polar Covalent
Bond Type Chart
DEN Range
Bond Type
0.0 – 0.3
Nonpolar Covalent
0.4 – 0.9
Moderately Polar Covalent
0.9 – 1.69
Very Polar Covalent
1.7 or greater
Ionic

34. Example 2 Determine the type of bond in LiBr
Find electronegativity of each atom
Li = 1.0 Paulings, Br = 3.0 Paulings
Find Electronegativity Difference (∆EN)
DEN = 3.0 – 1.0 = 2.0
Look at chart to determine bond type.
Bond Type: Ionic

35. Example 2 Determine the type of bond in O2
Find electronegativity of each atom

36. Electronegativity Chart

37. Example 2 Determine the type of bond in O2
Find electronegativity of each atom
O = 3.4 Paulings, O = 3.4 Paulings

38. Example 2 Determine the type of bond in O2
Find electronegativity of each atom
O = 3.4 Paulings, O = 3.4 Paulings
Find Electronegativity Difference (∆EN)
DEN = 3.4 – 3.4 = 0
Look at chart to determine bond type.

39. Moderately Polar Covalent
Bond Type Chart
DEN Range
Bond Type
0.0 – 0.3
Nonpolar Covalent
0.4 – 0.9
Moderately Polar Covalent
0.9 – 1.69
Very Polar Covalent
1.7 or greater
Ionic

40. Example 2 Determine the type of bond in O2
Find electronegativity of each atom
O = 3.4 Paulings, O = 3.4 Paulings
Find Electronegativity Difference (∆EN)
DEN = 3.4 – 3.4 = 0
Look at chart to determine bond type.
Bond Type: Nonpolar Covalent

41. CO 4. HF AlP 5. CaO N2 6. H2 How Polar Is It?
Determine the polarity of each bond in the following compounds by calculating the electronegativity difference for each:
CO HF
AlP CaO
N H2

42. Electronegativity Chart

43. Moderately Polar Covalent
Bond Type Chart
Range
Bond Type
0.0 – 0.3
Nonpolar Covalent
0.4 – 0.9
Moderately Polar Covalent
0.9 – 1.69
Very Polar Covalent
1.7 or greater
Ionic

44. Practice Time! Please finish the worksheet
Then, you can work on the Unit 3 Review Sheet
U3T Phase I Tomorrow!
U3T Phase II on Friday!

45. Exit Question Magnesium is a metal. Sulfur is a nonmetal.
What type of bond is formed between these elements?
Describe two ways that you could use to determine your answer to number 1.