Unit2Day5 VandenBout Tuesday October 01 2013 2 58 PM Vanden Bout LaBrake Crawford CH301 ELECTRONS and COMPOUNDS UNIT 2 Day 5 CH302 Vanden Bout LaBrake Fall 2012 Important Information HW06 Posted Due Tue 9AM LM19 Posted DUE Tue 9AM Laude LM Lecture 8 and LM Lecture 9 CH302 Vanden Bout LaBrake Spring 2012 Unit2Day5 VandenBout Page 1 What are we going to learn today Electron Configuration and Bonding Master using Lewis structures to predict bonding in compounds Employ the concept of resonance Use formal charge to help predict best possible Lewis structure CH302 Vanden Bout LaBrake Fall 2012 QUIZ CLICKER QUESTION 1 Referring to the position of Sr and P on the periodic table would you predict these elements would come together to A Form a metallic compound B Form a covalent compound C Form an ionic compound CH302 Vanden Bout LaBrake Fall 2012 Unit2Day5 VandenBout Page 2 QUIZ CLICKER QUESTION 1 Referring to the position of Sr and P on the periodic table would you predict these elements would come together to A Form a metallic compound B Form a covalent compound C Form an ionic compound CH302 Vanden Bout LaBrake Fall 2012 QUIZ CLICKER QUESTION 2 Naming Compounds Choose the formula that corresponds to strontium and phosphorus a b c d e SrP SrP2 Sr2P Sr3P2 Sr2P3 CH302 Vanden Bout LaBrake Fall 2012 Unit2Day5 VandenBout Page 3 QUIZ CLICKER QUESTION 3 Naming Compounds Choose the formula that corresponds to potassium dichromate a b c d e KCrO4 KCr2O7 K2CrO4 K2Cr2O7 K3Cr2O CH302 Vanden Bout LaBrake Fall 2012 QUIZ CLICKER QUESTION 4 Naming Compounds Choose the formula that corresponds to sulfur trioxide a b c d e SO SO32SO3 S2O3 SO42 CH302 Vanden Bout LaBrake Fall 2012 Unit2Day5 VandenBout Page 4 QUIZ CLICKER QUESTION 5 Naming Compounds Choose the formula that corresponds to sulfite a b c d e SO SO32SO3 S2O3 SO42 CH302 Vanden Bout LaBrake Fall 2012 QUIZ CLICKER QUESTION 6 Naming Compounds Choose the name that corresponds to NH4OH a b c d e nitrogen tetrahydrogen oxygen hyrdride nitrogen pentahydrogen oxide ammonium hydroxide ammonia oxyhydrogen hydronitrideoxide CH302 Vanden Bout LaBrake Fall 2012 Relate electron configuration to periodic table Unit2Day5 VandenBout Page 5 Relate electron configuration to periodic table Think About How Covalent Compounds Are Put Together Characterize the bond Bond Length Bond Strength Electron Pair Shared Equally YES PURE COVALENT NO POLAR COVALENT CH302 Vanden Bout LaBrake Fall 2012 What about compounds that aren t ionic Covalent How are they formed Are electrons lost No They are shared two non metals two elements with similar electronegativities Unit2Day5 VandenBout Page 6 How are they formed Are electrons lost No They are shared two non metals two elements with similar electronegativities CH301 Vanden Bout LaBrake Fall 2013 CH301 Vanden Bout LaBrake Fall 2013 Electronegativity electron pulling power of an atom when it is part of a molecule When one atom is more electronegative than another in a bond a polar covalent bond is formed Degree of polarity is dependent on difference in electronegativities Unit2Day5 VandenBout Page 7 CH301 Vanden Bout LaBrake Fall 2013 Ionic vs Covalent Bonds All bonds can be viewed as hybrids between purely ionic and purely covalent When two identical atoms are bound it is purely covalent When two different atoms are bound one may have a greater attraction for electrons and have a partial negative charge Polar covalent bond degree is measured as dipole moment When one atom has a much stronger attraction to the electrons than the other an electron may be donated yielding an ionic bond Unit2Day5 VandenBout Page 8 POLL CLICKER QUESTION 7 When drawing molecular structures a little dash between two atoms in the structure is representing a An ionic bond b A shared pair of electrons c A little stick or spring that you would use with a molecular model kit d A nonbonding pair of electrons CH302 Vanden Bout LaBrake Fall 2012 Covalent Compounds What is attached to what Valence electrons Lewis symbols Lewis Structure Satisfy the Octet H2 CH4 CH302 Vanden Bout LaBrake Fall 2012 LEWIS STRUCTURE RULES Determine total number of valence electrons Unit2Day5 VandenBout Page 9 LEWIS STRUCTURE RULES Determine total number of valence electrons Predict total number of Bonds S N A rule Draw Skeletal Structure Place nonbonding electrons Fix the number of bonds CH302 Vanden Bout LaBrake Fall 2012 Demonstrate using the rules to show how to put together Lewis structures CH4 C2H6 CH302 Vanden Bout LaBrake Fall 2012 Examples from Activity C2H4 C2H2 Unit2Day5 VandenBout Page 10 Examples from Activity C2H4 C2H2 CH302 Vanden Bout LaBrake Fall 2012 Take a little moment Bond Strength Bond Length Single Double Triple CH302 Vanden Bout LaBrake Fall 2012 Examples 4 5 and 6 from Activity C2H6O CH3OCH3 C2H5OH Unit2Day5 VandenBout Page 11 C2H6O CH3OCH3 C2H5OH CH302 Vanden Bout LaBrake Fall 2012 How can you be sure Formal Charge check FCatom Group bonds nonbonded e COCl2 COCl2 CH302 Vanden Bout LaBrake Fall 2012 Put these on the board Working for candy and fame NO3 Unit2Day5 VandenBout Page 12 Put these on the board Working for candy and fame NO3 CH302 Vanden Bout LaBrake Fall 2012 Resonance structures for the formate ion are shown below POLL CLICKER QUESTION 8 An average C O single bond is 0 143 nm in length An average C O double bond is 0 123 nm in length Which choice describes the actual bond lengths for the carbon oxygen bonds in a formate ion A Both carbon oxygen bonds are 0 133 nm B Both carbon oxygen bonds are 0 143 nm C One carbon oxygen bond is 0 143 nm and the other is 0 123 nm D Both carbon oxygen bonds switch between 0 123 nm and 0 143 nm CH302 Vanden Bout LaBrake Fall 2012 Unit2Day5 VandenBout Page 13 Think about it Ionic or covalent NaOH CH302 Vanden Bout LaBrake Fall 2012 Just when you were sure you had it nailed RnCl2 BeCl2 CH302 Vanden Bout LaBrake Fall 2012 Unit2Day5 VandenBout Page 14 CH302 Vanden Bout LaBrake Fall 2012 CH302 Vanden Bout LaBrake Fall 2012 Unit2Day5 VandenBout Page 15 What have we learned ATOMS BEHAVE IN CERTAIN PREDICTABLE WAYS WHICH CAN BE CORRELATED TO THE ELECTRON CONFIGURATIONS SATISFYING THE OCTET RULE IS A SOLID PREDICTOR OF BONDING IN IONIC AND COVALENT COMPOUNDS RESONANCE IS THE AVERAGE OF THE EXTREMES ELECTRONS ARE NOT TRAPPED IN THE LITTLE DASHES FORMAL CHARGE HELPS PREDICT BEST LEWIS STRUCTURE FOR A GIVEN MOLECULAR FORMULA CH302 Vanden Bout LaBrake Fall 2012 Learning Outcomes Draw the Lewis structures for molecular compounds
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