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.)