Catalyst – October 6(4), 2012 WAY BACK WEDNESDAY! 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 Celsius? 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

Today’s Agenda Catalyst Electronegativity Difference, Bond Type, and Bond Polarity Work Time Speed 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: ELECTRONEGATIVITY DIFFERENCE AND BOND TYPE

How to tell ionic and covalent apart Key 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 types Electronegativity 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 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

Pure Ionic Bonding I have no chance! 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 Find electronegativity of each atom

Electronegativity Chart

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

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.

Moderately Polar Covalent 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 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

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

Electronegativity Chart

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

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.

Moderately Polar Covalent 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 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

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 4. HF AlP 5. CaO N2 6. H2

Electronegativity Chart

Moderately Polar Covalent Bond Type Chart 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

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. What type of bond is formed between these elements? 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 What is a cation? What bond shares electrons? Complete the analogy: Opposite is to ionic as __________ is to covalent.

HW: Unit 3 Practice Test Questions (Half-Sheet) Today’s Agenda Catalyst Project Work Time Speed Dating Exit Question HW: 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), 2011 FUN 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: Salol B: Sodium Chloride (Salt) C: Copper (II) Sulfate D: 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?

Monday Mystery Element! Catalyst – October 22-1, 2011 Monday Mystery Element! Element’s Greek name means “moon” Added to dandruff shampoos Protects against cancer

Monday Mystery Element! Catalyst – October 22-1, 2011 Monday Mystery Element! Element’s Greek name means “moon” Added to dandruff shampoos Protects against cancer SELENIUM!

HW: STUDYYYYYYY FOR THE TEST TOMORROW!!!! Today’s Agenda Catalyst (New Groups after test) Gatorade/Powerade Test Unit 3 Test Review with Ms. Stroh Work Time Exit Question HW: STUDYYYYYYY FOR THE TEST TOMORROW!!!!

SWBAT get ready to DOMINATE tomorrow’s Unit 3 Test! 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 OF NAMING & FORMULAS!

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: 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 Metal Cation: Li Nonmetal Anion: O Li1+ O2-

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 Na2O CO2 CaBr Na2CO3 Mg3P2 K2S N2S3 Write formulas Carbon monoxide Barium nitrate Xenon difluoride Carbon tetrachloride Sodium carbonate Lithium fluoride Nitrogen trifluoride

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 4. HF AlP 5. CaO 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

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

Unit 3 Review Work Time Your Options: Not Your Option Review Sheet Extra Worksheets provided by Ms. Stroh Read book Not Your Option Wasting time and being unproductive

Exit Question What grade are you shooting for on this test? 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.)