Concept presentation on chemical bonding (iris lo)
CONCEPT PRESENTATION IONIC AND COVALENT BONDING (SCH3U) Presenter: Iris Lo Instructors: Janine Extavour & Marty Zatzman, OISE/UT
Overview Curriculum Expectations Common Misconceptions Curriculum Placement 4 Day Lesson Sequence Applications Teacher Resources
Curriculum ExpectationsSp e c ific Ex p e c ta tio ns : B2.1 – Use appropriate terminology related to chemical trends and chemical bonding, including, but not limited to: atomic radius, effective nuclear charge, electronegativity, ionization energy and electron affinity. B2.4 – Draw Lewis structures to represent the bonds in ionic and molecular compounds. B2.5 - Predict the nature of a bond (e.g., non-polar covalent, etc.) using electronegativity values of atoms. B2.6 - Build molecular models, and write structure formulae, for molecular compounds containing single and multiple bonds and for ionic crystalline structures. B3.4 – Explain the differences between the formulation of ionic bonds and the formation of covalent bonds. B3.5 – Compare and contrast the physical properties of ionic and molecular compounds.
Bonding Analogy Welcome to the Dr. Phil Show! Today we will be counseling 3 divorced couples Lisa Simpson and Milhouse Buzz Lightyear and Jessie Ken and Barbie Let’s have a look at how they interact to determine what is ‘bonding’ them together before we begin!
Couple #1 Milhouse is still very attracted to Lisa while she feels no attraction. Milhouse has taken sole custody of their child, Nelson, a factor that keeps them bonded together. Which bond does this couple represent (ionic, polar covalent or non-polar covalent)?
Couple #2 Buzz Lightyear is more attracted to Jessie than she is to him. Although this attraction is unequal, they Do still share a love for one another. They have joint custody of their son, Buzz Jr, with Buzz Jr. spending time primarily with his father. Which bond does this couple represent (ionic, polar covalent or non-polar covalent)?
Couple #3 This couple has equal attraction to each other They maintain their bond by having shared custody of their son, Ben. Ben spends an equal amount of time with both parents. Which bond does this couple represent (ionic, polar covalent or non- polar covalent)?
Common StudentMisconception #1 “Since both involve charges, the attraction between polar covalent molecules is the same as the attraction between ions in an ionic compound”Solutions: Emphasize that charges across polar covalent bonds are only p a rtia l charges Use the Dr. Phil bonding analogy
Common StudentMisconception #2 “The Lewis structure of covalent compounds gives the shape of the molecule.”Solutions: Reinforce that Lewis structure only shows atom linkage Have students build molecular models (modification: use gumdrops and toothpicks)
Common StudentMisconception #3 “When predicting bond type using electronegativity, there is a sharp divide between ionic and covalent bonds.”Solutions: Emphasize that the spectrum of electronegativity difference values is smooth Reinforce using a model of a bonding continuum and a table organizer showing percent ionic/covalent character for various ∆EN values
Common StudentMisconception #4 “The modern view of the atom is one in which the electrons circle the nucleus in fixed orbits, like the planets orbiting the sun.”Solutions: Make students aware that the models they are using is simplified Chemists describe electrons in terms of energy and probability of finding electrons within a region of space Use videos to help students visually Covalent Bonding Video Ionic Bonding Video
Curriculum Placement of theUnitMatter, Chemical Trends and Chemical Bonding unit: Matter, Chemical Trends and Chemical bonding unit is placed as the1st unit of the course Covers underlying basis of all other units Natural progression from grade 9 and 10 Chemistry Chemical Reactions suggested to be the 2nd unit Natural progression from grade 10 Chemistry Natural progression from Unit 1 - writing chemical formulas and naming of compounds needed for writing chemical equations, predicting chemical reaction products, etc.)
Concept Placement Within theUnit Placed after periodic trends and before writing chemical formulas and naming compounds Suggested order of the chemical bonding section: 1) Review: Bo hr m o d e l o f the a to m , io n fo rm a tio n, p ro p e rtie s o f io nic a nd m o le c ula r c o m p o und s 2) Introduce key underlying concepts: O c te t rule , Le wis s truc ture s 3) Introduce bonding overview: To give students some context 4) Intramolecular bonds: Ionic and covalent bonding 5) Intermolecular and Metallic Bonding
4 Day Lesson Sequence Day 1: Review & Classifying Chemical Compounds PowerPoint presentation: Bohr model of the atom Drawing Lewis structures Properties of ionic and covalent compounds. Demo: Test and compare the conductivity of salt solution and sugar solution Safety: Use low-voltage conductivity apparatus Group Activity: Bond With a Classmate Students act as positive and negative ions and form bonds with their peers. Introductory activity for day 2. Assessment: Informal question and answer (diagnostic) Lewis structure and Properties of Ionic/Covalent Compounds worksheet Predict, Observe, Explain Activity
Bond With a Classmate Activity: YourThoughts? In your table groups, discuss: a) Pros/cons of this activity? b) Ways to modify this activity for: -Different grade levels -Different streams (i.e. academic, applied, etc.)
Day 2: Introduction to Bonding PowerPoint presentation: Octet rule Electronegativity (including its periodic trend) Bonding continuum/characteristics of ionic, polar covalent, covalent bonds Video Clip on Bonding/Electronegativity Role-Play: Use the analogy of 3 couples going through relationship counseling to represent ionic, polar covalent and covalent bonding. Assessment: Informal question and answer Determine Bond Type Using Electronegativity worksheet Observation & feedback
Day 3: Ionic and Covalent Bonding Ionic Bonding PowerPoint presentation/Chalk and Talk: Formation of ions, Transferring single /multiple electrons & bonding involving > 2 ions (shown using Lewis structures/structural formulas), Properties of ionic compounds. Demo: Poker chips used to simulate ionic bonding. Video Clip: Ionic Bonding Covalent Bonding PowerPoint presentation (continuation): Single and multiple covalent bonding (shown using Lewis structures/structural formulas) Coordinate covalent bonds Exceeding the octet rule Properties of covalent compounds Compare/contrast ionic and covalent compounds. Demo: Poker chips used to simulate covalent bonding. Video Clip: Covalent Bonding
Day 3 (Cont’d) Assessment: Informal question and answer Drawing Lewis and Structural Diagrams of Ionic and Covalent Compounds worksheet
Day 4: Polar Covalent Bonding PowerPoint presentation: Polar covalent bonding (shown using Lewis structures and structural formulas) Polar/non-polar molecules, partial charges, and overall polarity Summary of all 3 bonds Demo: Place a charged ebonite rod next to water and then hexane. Water (polar) is attracted to the rod, hexane is not (non-polar) Safety: Hexane is a flammable liquid – do not place near open flames. Do not directly smell it. Use in well-ventilated area. Class discussion: Applications and societal implications. Lab: Gumdrop Molecular Models Build molecular models and draw the Lewis diagram, structural formulas and predicted shape of molecule for ionic and covalent compounds (Cherkas e t a l. , 2002). Safety: Students must not eat the candy if they are working with it in the lab.
Day 4 (Cont’d) Assessment and Evaluation: Informal question and answer (assessment) Polar Covalent Bonding worksheet (assessment) Predict, Observe, Explain Activity (assessment) Learning skills rubric (assessment) Lab worksheet (evaluation)
Concept Applications1 ) I ns a nd the Hum a n Bo d y o Humans depend on ions for their survival they are essential for maintaining good health2 ) Ca rbo n Dio x id e in So ft Drinks : ACo va le nt Co m p o und CO2 is somewhat soluble in water, especially at high pressures which is why soft drinks are bottled under pressure (Mustoe e t a l. , 2001). When you open a bottle of pop, some of the CO2 comes out of solution due to its low solubility (Mustoe e t a l. , 2001).3 ) A p lic a tio n o f Wa te r Po la rity : M ro wa ve p ic O ve ns Water is a polar molecule that is a good absorber of microwaves (Rayner-Canham, e t a l. , 2002). The energy is converted into heat to warm up food (Rayner-Canham, e t a l. , 2002).
Resources1) Nelson and McGraw-Hill Ryerson Chemistry 11 Teacher’s Resource Both provide: background info teaching suggestions (activities, tips/safety precautions for conducting labs, effective ways to approach the topic) answers to lab/textbook questions common misconceptions and solutions Prefer McGraw-Hill Ryerson Teacher’s Resource more detailed, includes strategies to support diverse student needs (ex. ESL students, etc.)
Resources (cont’d)2) Chemistry Games: J. Hand’s class website Provides pre-made review games3) Chalkbored: J. Schneider’s class website Provides PowerPoint presentations, handouts, labs, worksheets for grade 11 and 124) Chemistry Demonstrations: T. Sperring’s website Provides many quick Chemistry demos Materials, procedure and what should be observed are included
References1) Cherkas, A., Freure, C., George, T., Ivanco, J., Kisway, L., Plavetic, S.J., Stewart, J., and G. Wisnicki. (2002). M G ra w-Hill Ry e rs o n c Che m is try 1 1 Te a c he r’s Re s o urc e . Toronto: Mc-Graw-Hill Ryerson.2) Hand, J. (2010). Che m is try G a m e s . Retrieved July 9, 2010, from <http://www.mansfieldct.org/schools/mms/staff/hand/chemgames.htm>3) Jenkins, F., van Kessel, H., Davies, L., Lantz, O., Thomas, P., and D. Tompkins. (2002). N ls o n Che m is try 1 1 . Toronto: Nelson e Thomson Learning.4) Jenkins, F., van Kessel, H., Davies, L., Sanader, M., Tompkins, D., Lantz, O., and S. Haberer. (2002). N ls o n Che m is try 1 1 e Te a c he r’s Re s o urc e . Toronto: Nelson Thomson Learning.5) Mustoe, F., Jansen, M., Doram, T., Ivanco, J., Clancy, C., and A. Ghazariansteja. (2001). M G ra w-Hill Ry e rs o n Che m is try c 1 1 . Toronto: McGraw-Hill Ryerson Limited.6) Rayner-Canham, G., Damju, S., and U. Goering-Boone. (2002). A d is o n We s le y Che m is try 1 1 . Toronto: Addison Wesley. d7) Schneider, J. (2009). Cha lkbo re d : Che m is try 1 1 . Retrieved July 9, 2010, from <http://www.chalkbored.com/lessons/chemistry-11.htm>8) Sperring, T. (2000). Che m is try De m o ns tra tio ns . Retrieved July 9, 2010, from <http://webcache.googleusercontent.com/search?q=cache:vRVGMG9e6HcJ:alex.edfac.usyd.edu.au/methods/scien ce/Chemistry%2520Demonstrations+water,+ebonite+rod,+hexane&cd=1&hl=en&ct=clnk&gl=ca>