Name IMF Unit RAQ 1 Fill in the Molecular Orbital diagram for CO Please state the bond order Please state whether this compound is expected to be paramagnetic or diamagnetic Please identify on the drawing the location of the HOMO and the LUMO Carbon has 6 total electrons Oxygen has 8 total electrons BO Bonding Antibonding BO 10 4 3 Diamagnetic Outcomes 9 10 11 12 2 From the line drawing write the correct molecular formula State the valence bond hybridization around the central atoms where indicated with an arrow In addition state the electronic geometry and molecular geometry around each of these central atoms State the number of pi bonds Circle the regions containing delocalized bonds B A C D Correct Molecular Formula C15H16N3OCl A sp2 trigonal planar electronic trigonal planar molecular B sp2 trigonal planar electronic bent molecular C sp3 tetrahedral electronic tetrahedral molecular D sp3 tetrahedral electronic tetrahedral molecular Revised SH 7 14 13 LaBrake Vanden Bout 2013 Name pi bonds 7 according the valence bond theory The circled region is ONE large delocalized pi system according the MO theory Outcomes 1 2 3 4 5 6 3 Fully describe macroscopic and molecular view with words and pictures the two solids I2 mp 386 K and KI mp 959 K I2 Molecular Solid Only non metals Non polar molecules Held together by dispersion forces only Solid at room temp because the large iodine atoms have a lot of electrons making the I2 molecules highly polarizable KI Ionic Solid Metal and non metal Columbic attractions ionic interactions hold the solid together Crystal lattice structure of alternating K cations and I anions Solid is not a good conductor but in liquid form or when dissolved KI is a good conductor Revised SH 7 14 13 LaBrake Vanden Bout 2013 Name Purple K cations Green I anions Outcomes 13 17 18 4 Propanol CH3CH2CH2OH and Glycerol CH2OHCH2OHCH2OH are both considered to be alcohols While they both exist as liquids at room temperature their liquid properties are different Explain how you expect the properties to be different Support your answer with a full molecular explanation Propanol Glycerol Surface Tension Glycerol greater than propanol Viscosity Glycerol greater than propanol Vapor Pressure Glycerol less than propanol Boiling Point Glycerol greater than propanol Glycerol and propanol contain the same number of carbons but glycerol has three times the amount of OH groups and therefore MUCH more hydrogen bonding interactions between molecules This stronger IMF influence holds the glycerol molecules together better Outcomes 8 13 14 15 5 Given the following data provide a molecular view description of the trend in boiling points based on all intermolecular forces for the given molecules In your answer include whether or not each compound exists as a solid liquid or gas at room temperature Compound Boiling Point Melting Point CHF3 191 K 26 K Gas at RT CHCl3 334 K 210 K Liquid at RT CHBr3 415 K 319 K Solid at RT CHI3 490 K 396 K Solid at RT Revised SH 7 14 13 LaBrake Vanden Bout 2013 Name As we look down the table halides increase in size and therefore in polarizability The more polarizable the greater the dispersion forces are between molecules The compounds lower in the table have stronger dispersion IMFs All of the compounds also have dipole dipole IMFs but the IMF that is most influential in the differences observed here is the dispersion forces NONE of the compounds have hydrogen bonding The hydrogens are always bonded to the carbon in these molecules and for hydrogen bonding to exist the hydrogen must be bonded directly to F O or N Outcomes 8 13 15 16 17 18 6 To fully prepare for this test you should be able to explain the following I Describe the difference similarities between a polar bond and a polar molecule Polar Bond Electronegativity difference between two atoms Polar Molecule A permanent net dipole moment Both Have partial positive and partial negative areas Outcomes 7 8 Revised SH 7 14 13 LaBrake Vanden Bout 2013 Name II Describe the differences similarities between a bond and an intermolecular force Include in your description the term hydrogen bond in the context of IMFs Bond Within a molecule Covalent bonds are shared electrons Ionic bonds are electrostatic interactions between charged species IMF Between molecules IMFs are electrostatic interactions too but weaker Hydrogen bonding is an IMF because it occurs between molecules See picture below of methanol molecules H bonding Outcomes 13 III Describe the differences similarities between polar and polarizable Polar Fixed dipole moment Molecular geometry can be important Polarizable The ability to have induced dipole moments Increases with size Outcomes 16 IV Describe the differences similarities between molecule and molecular solid and covalent solid Molecule A single discrete unit of atoms Example One water molecule H2O Revised SH 7 14 13 LaBrake Vanden Bout 2013 Name Molecular Solid Comprised of non metals Many individual discrete molecules held together by IMFs Usually a low MP and BP Example An ice cube lots of water molecules Covalent Solid Comprised of non metals Covalently bound network of nonmetals Usually high MP and BP Example Quartz is a network of SiO2 Outcomes 17 18 V Explain the relationship between boiling point vapor pressure and the Boltzmann distribution of KE s for a liquid at given temperature in the context of IMFs For any liquid the molecules have a distribution of Kinetic Energies If a molecule has enough kinetic energy if can escape from the IMFs it experiences in liquid phase If it is at the surface it will escape into the gas phase The weaker the IMFs the more molecules a higher percentage at any given temperature can escape into the gas phase For example propanol has a higher vapor pressure than glycerol because it experiences fewer hydrogen bonding interactions see 4 A greater percentage of propanol molecules will be found in the gas phase compared to glycerol at any given temperature because its IMFs are weaker Higher vapor pressure lower boiling point Lower vapor pressure higher boiling point Outcomes 15 Revised SH 7 14 13 LaBrake Vanden Bout 2013 Name Place the following outcomes next to the problems on this sheet Students will be able to 1 apply the VSEPR model to determine a molecule s electronic geometry and molecular geometry from its Lewis dot structure 2 apply the VB model to give the atomic hybridization of any atom in a given molecule 3 use the VB model to describe any bond in a
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