Unit 6 Chem Learning Targets

Learning Targets Review: I CAN draw the Lewis Dot Structure of an atom, ionic compound and a covalent molecule, indicating valence electrons and bonds I CAN describe VSEPR theory and explain how it affects lone pairs and bonded pairs in a molecule. I CAN state and model the basic shapes of a covalent molecule (both 2D and 3D) using diagrams and molecular modeling kits I CAN predict the shape of a molecule based on the formula I CAN state the bond angle between two given atoms in a molecule I CAN classify a bond as nonpolar covalent, polar covalent, or ionic using an electronegativity chart I CAN define a polar bond, explain why they form and compare its characteristics with a nonpolar bond I CAN predict the polarity of a molecule based on the formula I CAN define and explain polymers (formation and composition) and describe how polymers are useful in the real-world. Chemistry Important Dates! Monday March 6 Tuesday 7 Wednesday 8 Thursday 9 Friday 10 Saturday 11 Sunday 12 15 13 14 16 17 18 19 25 26 Early Dismissal 24 20 21 22 23 NO SCHOOL Review of Bonding: Lewis Dot Structures Draw a Lewis Dot Structure for each of the following atoms: C H Al Cl Mg Na O Ca Draw a Lewis Dot Structure for the following compounds and name them. Identify the types of bonds (ionic or covalent) in each compound. H2 K2O Cl2 SCl2 MgS Al2O3 KI Cs3N NCl3 PH3 SiS2 PCl3 Notes on VSEPR TheoryDraw ALL of the examples. Include the names of the shapes and the bond angles for each. Go to http://phet.colorado.edu and click play with simulationsOn the left-hand side, click by device and then ChromebookScroll down and click Molecule Shapes, then start the simulation by pressing playClick Model, then click the yellow “remove all” button on the right-hand sideCheck the box for molecular geometry (bottom) and the box for show bond angles (right)Molecular Instructions: Shapes Simulation Modeling: Using the simulation, complete the chart below. Feel free to rotate the molecule by clicking and dragging it. # of Bonds Attached to Central Atom # of Lone Pairs on Central Atom 1 0 2 0 3 0 4 0 3 1 2 2 Molecular Geometry Bond Angles 3-D Drawing Examples Real Molecules: Click the real molecules button at the bottom of the page. Using the molecule drop down menu, go through and find real molecule examples to add to the above chart. Molecular Shapes Practice Formula H2S SCl2 NCl3 SiCl4 Name of Molecule Lewis Dot Structures Molecular Geometry Bond Angle CS2 NH3 CH2O Notes on Bond PolarityDraw ALL of the examples!Bond Polarity Practice What is the difference between a polar covalent bond and a nonpolar covalent bond in terms of how they share their electrons? What is the difference between a polar covalent bond and a nonpolar covalent bond in terms of electronegativity values? What is a partial charge called? Draw an example below. What is the difference between a polar covalent bond and an ionic bond? Describe the following bonds as nonpolar covalent, polar covalent, or ionic: CH 4 HF Na 2 O Notes on Molecular PolarityDraw ALL of the examples!Molecular Polarity Practice Explain why carbon dioxide is a nonpolar molecule even though its bonds are polar. (Hint: draw a Lewis Dot Structure to start!) Divide the following molecules into two categories: polar covalent bonds and nonpolar covalent bonds ? (Hint: use an electronegativity chart) N 2 HF F 2 NO FCl Polar Covalent Bonds Divide the following molecules into two categories: polar and nonpolar molecules . Nonpolar Covalent Bonds N 2 HF F 2 NO FCl Polar Molecule Nonpolar Molecule Molecular Polarity Simulation Search Google for “PhET”. Click on the link and search for the Polarity Lab. Open the simulation by clicking the “Run Now” Icon. Introduction: In this atomic-level simulation, you will investigate how atoms' electronegativity value affects the bonds they produce. When two nonmetals bond, a pair of more of electrons are shared between atoms. Electronegativity is a measure of a single atom's ability to pull electrons shared in a bond with another atom. 1) From what you've already learned about trends of the periodic table, what would cause an atom to have a high electronegativity value? 2) How do additional energy levels affect an atoms’ electronegativity value? Procedure: 1) Turn on (check) all view options on the right. In the surface category, click Electrostatic Potential Create the following situations by dragging the slider above each atom changing the electronegativity values: Describe in detail the bond character, charges, dipoles, and any other characteristics of the situations following: 2) Atom A: High electronegativity, Atom B: Low electronegativity: a) Specifically, where are the charges found in this molecule? (Electrostatic Potential– who is +? and who is -?) b) Where does the dipole point to? c) Describe the polarity of the bond: (Polar Covalent/Nonpolar Covalent/Ionic) 3) Atom A: Low electronegativity, Atom B with an average (middle position) electronegativity: a) Specifically, where are the charges found in this molecule? (Electrostatic Potential– who is +? and who is -?) b) Where does the dipole point to? c) Describe the polarity of the bond: (Polar Covalent/Nonpolar Covalent/Ionic) 4) Atom A: High electronegativity, Atom B: High electronegativity: a) Specifically, where are the charges found in this molecule? (Electrostatic Potential– who is +? and who is -?) b) Where does the dipole point to? c) Describe the polarity of the bond: (Polar Covalent/Nonpolar Covalent/Ionic) 7) Describe (in your own words) what is meant by each the dipoles, ?- and ?+. In the surface box to the right, switch the view to electron density: Experiment with different situations. 8) Describe the density of electrons around positively charged atoms compared to the density of electrons around negatively charged atoms. 9) A bond is characterized as ionic or covalent by comparing the differences between two atoms' electronegativities. Describe an ionic bond in terms of the atoms' electronegativity values. (Don’t write numbers) 10) Describe a covalent bond in terms of the atoms' electronegativity values. (Don’t write numbers) 11) Additionally, we further separate covalent bonds into polar covalent and nonpolar covalent. What is true about the electronegativity difference for a nonpolar covalent bond? (Don’t write numbers) Switch the tab at the top to three atoms: In the view category, click on all items! In this simulation realize that in addition to changing the electonegativities, you may also move individual atoms by dragging them with the mouse. 12) Describe how a molecule with strong polar bonds could have no molecular dipole at all? 13) Experiment with the three atoms simulation. Choose two situations where the atoms have different electronegativites, and different angles between each atom. Illustrate those situations below including each atom’s electronegativity, draw the bond polarities (bond dipoles), and draw the molecule’s polarity (molecular dipole). Atom A Atom B Atom C Atom A Atom B Atom C Electroneg. Electroneg. Electroneg. Electroneg. Electroneg. Electroneg. Switch tabs to Real Molecules: View all items and switch surface to Electrostatic Potential. Using the simulation, examine each molecule and indicate P for Polar and NP for nonpolar in the table below: ****Notice that some molecules have been omitted and you will need to skip them!!!****** Molecule H2 N2 O2 F2 HF H2O CO2 HCN O3 NH3 CH2O CH4 CH3F CH2F2 CHF3 CF4 CHCl3 Bond Polarity (Between Atoms) Molecule Polarity (Symmetry) Molecular Polarity Practice Formula Lewis Dot Structures Molecular Shape and Bond Angle Bond Polarity Molecule Polarity NF3 SiO2 NCl3 CH2O CF4 H2O PH3 Polymer Webquest Search for “Microworlds Kevlar” and click on the first link, or type the address: www2.lbl.gov/MicroWorlds/Kevlar On the main page, what are some of the uses for Kevlar? Click on the blue button next to “Clue #1” at the bottom of the page. What are some examples of synthetic polymers? Define what a monomer is. Define what a polymer is. Click on the box that says “Activity” underneath the paragraph of text. Sketch an example of linear, branched, and cross-linked polymers. Where do we find linear and branched polymers in our lives? Click the Back button and then click the blue button next to “Clue #2” at the bottom of the page. Which form of spaghetti is stronger: the tangled mess or the straight stack? How do we make Kevlar fibers in this way? Click on the blue button next to “Clue #3” at the bottom of the page. Describe the two features of Kevlar fibers that give them their strength. Click on the blue button next to “Clue #4” at the bottom of the page. Click on the “Activity” button. Use pieces of tape from one of the dispensers and do the experiment. How does this demonstrate Hydrogen bonding? Click the back button. Click the blue button next to “Putting the Pieces Together.” Read through the summary of why Kevlar ends up being so strong. Make a bullet pointed summary. Unit 6 Review: Molecular Geometry and Polymers Compound Lewis Dot Structure Molecular Shape Bond Angle Bond Polarity Molecular Polarity NH3 SH2 CF4 CS2 CO2 NCl3 Li2S