catalyst – february (72-46)/2, 2011 way back wednesday! hw out! 1. what is the mass of an atom...
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Catalyst – February (72-46)/2, 2011WAY BACK WEDNESDAY! HW OUT!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 Cesius?
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
CatalystReview Naming and FormulasElectronegativity Difference, Bond Type, and Bond Polarity
Review = Time to WORKExit Question
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!
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:Use prefixes, 2nd
element ends in -ide
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!
A compound made from Lithium and Oxygen
How do we know if it is ionic or covalent? Metals and non-metals make ionic compounds
Naming Ionic Compounds
Ionic Bond
Cation: Li Anion: O
Li O
Ionic Bond
Cation: Li Anion: O
Li+ O2-
Ionic Bond
Li+ O2-
Cation: Li Anion: O
Ionic Bond
Cation: Li Anion: O
Li2O
MgO
Naming Ionic CompoundsMgO
Magnesium Oxide
NBr3
Naming Covalent Compounds
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 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).
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 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!
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 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 – 0.3 Nonpolar Covalent
0.4 – 0.9 Moderately Polar Covalent
0.9 – 1.69 Very Polar Covalent
1.7 or greater Ionic
Example 2
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 – 0.3 Nonpolar Covalent
0.4 – 0.9 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 – 0.3 Nonpolar
Covalent0.4 – 0.9 Moderately
Polar Covalent0.9 – 1.69 Very Polar
Covalent1.7 or greater Ionic
Practice Time!
Please finish the worksheetThen, you can work on the Unit 3 Review Sheet
U3T Phase I Tomorrow!U3T Phase II on Friday!
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.