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Catalyst – October 6(4), 2012WAY BACK WEDNESDAY! 1. What is the mass of an atom that has 14
protons and 15 neutrons?2. 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 Celsius?
a) Less gas will be producedb) Gas will be produced for more than 1 minutec) The reaction will have a strong odord) The reaction will not occur
Today’s Agenda
CatalystElectronegativity Difference, Bond Type, and Bond Polarity
Work TimeSpeed Dating???Exit Question
HW: Study for Test!
Today’s Objectives
SWBAT determine bond type using electronegativity differences (∆EN).
SWBAT classify compounds as ionic or covalent, describe characteristics, and write names and formulas correctly.
SWBAT get ready to DOMINATE the Test tomorrow!!!!
NOTES TITLE:ELECTRONEGATIVIT
Y DIFFERENCEAND BOND TYPE
How to tell ionic and covalent apartKey Point #1: Along with looking at the formula and name for a compound, we can also look at electronegativity differences (∆EN) in order to determine bond type (ionic or covalent).
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
typesElectronegativity Chart
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
Electronegativity Chart
Pauling Values
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
Bond Polarity Terms to KnowPure 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
Pure Ionic Bonding Total give and take (transfer) of electrons!
= Big ∆EN!
I have no
chance!
Covalent Bonding is like a Tug-of-War
The more electronegative atom will pull electrons harder
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
Polarity Ranges
Key Point #3: Bonds are not always purely ionic (I) or purely covalent (NPC). They could be slightly ionic (VPC) or slightly covalent (MPC).
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
Bond Type Chart – Copy into notes!
∆EN 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
Example 1
Determine the type of bond in LiBr
1. Find electronegativity of each atom
Electronegativity Chart
Example 1
Determine the type of bond in LiBr
1. Find electronegativity of each atom
Li = 1.0 Paulings, Br = 3.0 Paulings
Example 1
Determine the type of bond in LiBr
1. Find electronegativity of each atomLi = 1.0 Paulings, Br = 3.0 Paulings
2. Find Electronegativity Difference (∆EN)DEN = 3.0 – 1.0 = 2.0
3. Look at chart to determine bond type.
Bond Type Chart
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
Example 1
Determine the type of bond in LiBr
1. Find electronegativity of each atomLi = 1.0 Paulings, Br = 3.0 Paulings
2. Find Electronegativity Difference (∆EN)DEN = 3.0 – 1.0 = 2.0
3. Look at chart to determine bond type.
Bond Type: Ionic
Example 2
Determine the type of bond in O2
1. Find electronegativity of each atom
Electronegativity Chart
Example 2
Determine the type of bond in O2
1. Find electronegativity of each atom
O = 3.4 Paulings, O = 3.4 Paulings
Example 2
Determine the type of bond in O2
1. Find electronegativity of each atomO = 3.4 Paulings, O = 3.4 Paulings
2. Find Electronegativity Difference (∆EN)DEN = 3.4 – 3.4 = 0
3. Look at chart to determine bond type.
Bond Type Chart
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
Example 2
Determine the type of bond in O2
1. Find electronegativity of each atomO = 3.4 Paulings, O = 3.4 Paulings
2. Find Electronegativity Difference (∆EN)DEN = 3.4 – 3.4 = 0
3. Look at chart to determine bond type.
Bond Type: Nonpolar Covalent
How Polar Is It?
Determine the polarity of each bond in the following compounds by calculating the electronegativity difference for each:
1. CO 4. HF2. AlP 5. CaO3. N2 6. H2
Electronegativity Chart
Bond Type Chart
Range Bond Type0.0 – 0.39 Nonpolar
Covalent0.4 – 0.89 Moderately
Polar Covalent0.9 – 1.69 Very Polar
Covalent1.7 or greater Ionic
Practice Time!
Please finish the worksheet
Exit Question
Write one thing you will do today/tonight to get ready to DOMINATE the Test tomorrow.
Then doooo it!
Exit Question
Magnesium is a metal. Sulfur is a nonmetal.
1. What type of bond is formed between these elements?
2. Describe two ways that you could use to determine your answer to number 1.HW: Review Chapter 12,
Review Sheet, STUDY!
Catalyst – September 23+6, 2011
1. What is a cation?2. What bond shares electrons?3. Complete the analogy:
Opposite is to ionic as __________ is to covalent.
Today’s Agenda
CatalystProject Work TimeSpeed DatingExit QuestionHW: Unit 3 Practice Test
Questions (Half-Sheet)
Today’s Objectives
SWBAT complete AWESOME Chemistry.com Projects.
SWBAT find love in Speed Dating!
Speed Dating
Half of you will remain STATIONARY Half of you will rotate IN ORDER,
CLOCKWISE You will have 4 minutes with each
“date” Ask each other questions to
determine if your atoms have a potential love match!
Exit Question
Catalyst – September 5(6), 2011FUN GRAPH FRIDAY!
What are TWO questions you could ask when looking at this graph?
Today’s Agenda
Catalyst HW Review Ionic vs. Covalent Lab! Do Gatorade or Powerade
Conduct Electricity? Group of the Week Exit Question
Today’s Objectives
SWBAT conduct an experiment to determine if unknown substances are ionic or covalent.
Today’s Lab
Safety: Be careful with hotplates. Be Goggle Gangsters!
Alternate between heating and conductivity tests
Unknown Substances
A: SalolB: Sodium Chloride (Salt)C: Copper (II) SulfateD: Sucrose (Sugar)
Salol
Chemical Name: Phenyl salicylate Chemical Formula: C13H10O3
Melting Point: 41.5˚C
Sodium Chloride (Salt)
Chemical Name: Sodium Chloride Chemical Formula: NaCl Melting Point: 861˚C
Copper (II) Sulfate
Chemical Name: Copper (II) Sulfate Chemical Formula: CuSO4
Melting Point: 110˚C
Sucrose (Sugar)
Chemical Name: Copper (II) Sulfate Chemical Formula: C12H22O11
Melting Point: 186˚C
Exit Question
We have just officially entered the Fall season. What is your favorite season and why?
Catalyst – October 22-1, 2011
Monday Mystery Element!
1.Element’s Greek name means “moon”
2.Added to dandruff shampoos
3.Protects against cancer
Catalyst – October 22-1, 2011
Monday Mystery Element!
1. Element’s Greek name means “moon”
2. Added to dandruff shampoos
3. Protects against cancer SELENIU
M!
Today’s Agenda
Catalyst (New Groups after test) Gatorade/Powerade Test Unit 3 Test Review with Ms. Stroh Work Time Exit QuestionHW: STUDYYYYYYY FOR THE
TEST TOMORROW!!!!
Today’s Agenda
SWBAT get ready to DOMINATE tomorrow’s Unit 3 Test!
Unit 3– What You Need to Know…
Ionic, Covalent, Metallic Similarities and Differences Characteristics of Ionic and Covalent
Octet Rule Lewis Dot Structures for Ions and Compounds Ionic Formulas and Names
Kriss-Kross, No Prefixes, Transition Metals, Polyatomic Ions
Covalent Formulas and Names No Kriss-Krossing, Formula Subscripts = Name Prefixes
Determining Bond Type with Electronegativity Difference
Get to Know Your Compounds Partner up with someone in your
group Ask each other, “If you were a
chemical compound, would you want to be ionic or covalent and why?”
Be ready to share each other’s answer
Octet Rule
While bonding, atoms will give, take, and/or share electrons in order to have a full valence (outer) shell (2 or 8 electrons)
Lewis Dot Structures
Draw the LDS for the following atoms and ions… Mg, S, Br, Al, O2-, K1+ , C4+
Model the ionic bond formation for… Lithium chloride
Draw the LDS for the covalent compounds… SiF4, H2S, CO, SO
REVIEW OFNAMING &
FORMULAS!
Yo Yo! Let’s break it down!
IONICMetal + Nonmetal
Writing Formulas:Kriss Kross chargesNaming:2nd element ends in
–ide, ignore subscripts
COVALENTNonmetal + NonmetalWriting Formulas:Prefixes = subscript #sNaming:2nd element ends in –
ide, don’t ignore subscripts – use prefixes
How do we know if our compound is ionic or covalent?
Is it between a metal and a non-metal? YES!!! Then, it is ionic!!!
Is it between a non-metal and a non-metal? Then, it is covalent!
Ionic Bond
Metal Cation: Li
Nonmetal Anion: O
Li O
Ionic Bond
Metal Cation: Li
Nonmetal Anion: O
Li1+ O2-
Ionic Bond
Li1+ O2-
Metal Cation: Li
Nonmetal Anion: O
Ionic Bond
Metal Cation: Li
Nonmetal Anion: O
Li2O
MgO
MgO
Magnesium Oxide
NBr3
NBr3
Nitrogen tribromide
Write the names and formulas…First! Decide if it’s ionic or covalent!
Write names
1. Na2O2. CO2
3. CaBr
4. Na2CO3
5. Mg3P2
6. K2S7. N2S3
Write formulas
1. Carbon monoxide2. Barium nitrate3. Xenon difluoride4. Carbon tetrachloride5. Sodium carbonate6. Lithium fluoride7. Nitrogen trifluoride
How Polar Is It?
Determine the polarity of each bond in the following compounds by calculating the electronegativity difference for each:
1. CO 4. HF2. AlP 5. CaO3. N2 6. H2
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
Polarity Ranges
Bonds are not always purely ionic (I) or purely covalent (NPC). They could be slightly ionic (VPC) or slightly covalent (MPC).
Electronegativity Chart
Bond Type Chart
Range Bond Type0.0 – 0.3 Nonpolar
Covalent0.4 – 0.9 Moderately
Polar Covalent0.9 – 1.69 Very Polar
Covalent1.7 or greater Ionic
Unit 3 Review Work Time
Your Options: Review Sheet Extra Worksheets provided by Ms.
Stroh Read book
Not Your Option Wasting time and being
unproductive
Exit Question
1. What grade are you shooting for on this test?
2. What do you plan to actually do today/tonight in order to prepare for the test? (Some options: study on your own, study with a friend, complete review sheet, read book, come at lunch or after school for tutoring, etc.)