Week 5 – Day 4 – 2013- Bond Interactions – 2
Chemical bonds vs. intermolecular interactions The three chemical bonds the mix imbetween The three intermolecular interactions metallic bonds covalent bonds ionic bonds polar-covalent bonds ~ 400 kJ/mol ~ 400 kJ/mol ~ 400 kJ/mol visible light 170-290 kJ/mol ion-dipole heavy main group dispersion 50-200 kJ/mol 5-100 kJ/mol FH…H hydrogen bonds OH…H hydrogen bonds NH…H hydrogen bonds room temperature dipole-dipole interactions light main group dispersion ~150 kJ/mol ~ 20 kJ/mol ~10 kJ/mol 2.5 kJ/mol 1-5 kJ/mol < 1 kj/mol The three chemical bonds the mix imbetween The three intermolelcular interactions metallic bonds covalent bonds ionic bonds polar-covalent bonds ~ 400 kJ/mol ~ 400 kJ/mol ~ 400 kJ/mol visible light 170-290 kJ/mol ion-dipole heavy main group dispersion 50-200 kJ/mol 5-100 kJ/mol FH…H hydrogen bonds OH…H hydrogen bonds NH…H hydrogen bonds room temperature dipole-dipole interactions light main group dispersion ~150 kJ/mol ~ 20 kJ/mol ~10 kJ/mol 2.5 kJ/mol 1-5 kJ/mol < 1 kj/mol dispersion interactions the third intermolecular interaction: strong vs. weak dispersion interactions Br boiling point: 59o C no dipoles and no hydrogen bonds in F2, Cl2, Br2 or I2. F Br I boiling point: 184o C F boiling point: -188o C Cl boiling point: -34o C Cl I Strong vs. weak dispersion interactions F F b.p. -188o C F−F Br Cl Cl b.p.-34o C Cl − Cl Br b.p. 59o C Br − Br I I b.p. 184o C I−I The four Lewis structures are all similar. No dipoles; No ions; No hydrogen bonds Please rationalize the different boiling points of the noble gases. covalent bonds ionic bonds polar-covalent bonds the one mix imbetween ~ 400 kJ/mol ~ 400 kJ/mol ~ 400 kJ/mol visible light 170-290 kJ/mol ion-dipole heavy main group dispersion 50-200 kJ/mol 5-100 kJ/mol FH…H hydrogen bonds OH…H hydrogen bonds NH…H hydrogen bonds room temperature dipole-dipole light main group dispersion ~150 kJ/mol ~ 20 kJ/mol ~10 kJ/mol 2.5 kJ/mol 1-5 kJ/mol < 1 kj/mol NaCl (solid) Na+ (aqueous) + Cl- (aqueous) ~200 kJ/mole ~400 kJ/mol ion-ion bond ~400 kJ/mol Ion–dipole interaction ~100- 200 kJ/mol. The three chemical bonds the mix imbetween The three intermolecular interactions metallic bonds covalent bonds ionic bonds polar-covalent bonds ~ 400 kJ/mol ~ 400 kJ/mol ~ 400 kJ/mol visible light 170-290 kJ/mol ion-dipole heavy main group dispersion 50-200 kJ/mol 5-100 kJ/mol FH…H hydrogen bonds OH…H hydrogen bonds NH…H hydrogen bonds room temperature dipole-dipole interactions light main group dispersion ~150 kJ/mol ~ 20 kJ/mol ~10 kJ/mol 2.5 kJ/mol 1-5 kJ/mol < 1 kj/mol the three chemical bonds, the three intermolecular interactions and the one mix imbetween ~400 kJ/mole ~400 kJ/mole I boiling point: 184o C I F boiling point: -188o C ~200 kJ/mole The three chemical bonds the mix imbetween The three intermolecular interactions metal bonds covalent bonds ionic bonds polar-covalent bonds ~ 400 kJ/mol ~ 400 kJ/mol ~ 400 kJ/mol visible light 170-290 kJ/mol ion-dipole heavy main group dispersion 50-200 kJ/mol 5-100 kJ/mol FH…H hydrogen bonds OH…H hydrogen bonds NH…H hydrogen bonds room temperature dipole-dipole light main group dispersion ~150 kJ/mol ~ 20 kJ/mol ~10 kJ/mol 2.5 kJ/mol 0.5-3 kJ/mol < 1 kj/mol heavy main group dispersion bond dipole moments F-H…F O-H…O ion-ion light main group dispersion Qatar Connecticut corresponds to room temperature bonds vs. intermolecular interactions covalent bonds ionic bonds polar-covalent bonds metal bonds ~ 400 kJ/mol ~ 400 kJ/mol ~ 400 kJ/mol visible light 170-290 kJ/mol ion-dipole heavy main group dispersion 50-200 kJ/mol 5-100 kJ/mol FH…H hydrogen bonds OH…H hydrogen bonds NH…H hydrogen bonds room temperature dipole-dipole interactions light main group dispersion ~150 kJ/mol ~ 20 kJ/mol ~10 kJ/mol 2.5 kJ/mol 1-5 kJ/mol < 1 kj/mol What are each of the types of interactions/bonds below? Na+ … Cl- H3C-SiH3 …. …. H-C≅N Mg2+… O2- N≅C-H F-H ….OH2 Mg2+… OH2 - H2Te … TeH2 What interaction holds together the following pairs of molecules? What is roughly the energy of interaction in kJ/mole? a) b) two NF3 molecules two BiF3 molecules c) two F2 molecules d) two HF molecules e) an H2O molecule and an HF molecule f) two CH4 molecules covalent bonds ionic bonds polar-covalent bonds metallic bonds ~ 400 kJ/mol ~ 400 kJ/mol ~ 400 kJ/mol visible light 170-290 kJ/mol ion-dipole heavy main group polarization 50-200 kJ/mol 5-100 kJ/mol FH…H hydrogen bonds OH…H hydrogen bonds NH…H hydrogen bonds room temperature dipole-dipole (< 2 D, Dc 1st-2nd row) light main group polarization ~150 kJ/mol ~ 20 kJ/mol ~10 kJ/mol 2.5 kJ/mol 0.5-3 kJ/mol < 1 kj/mol heavy main group dispersion Are X and Y 1st and 2nd row elements? no Do heavy main group interactions exist? yes yes Do F-H…F bonds exist? no Do O-H…O bonds exist? yes Do N-H…N bonds exist? no yes yes covalent bond no F-H…F light main group polarization O-H…O yes N-H…N Calculate Dc Is Dc < 0.5 Debye? dipole-dipole interaction yes Is Dc > 1 Debye? What interaction holds together the following pairs of molecules? What is roughly the energy of interaction in kJ/mole? a) b) two NF3 molecules two BiF3 molecules c) two F2 molecules d) two HF molecules e) an H2O molecule and an HF molecule f) two CH4 molecules For now compare boiling points for molecules with roughly the same molecular mass. Why do the boiling points occur in the order in which they do? Where would formic acid, HCO2H with molecular weight 46 g/mol appear on this boiling point chart? How would CH3SeSeCH3 and I2 approach one another? How would RSeSeR and I2 approach one another? Salad dressing is composed of oil and vinegar (that is hydrocarbons, CH3(CH2)nCH3, water, and acetic acid, CH3COOH. Why do oil and vinegar not mix? A typical soap compound is sodium stearate. Why is soap good at removing the oil from the skin? sodium stearate A typical soap compound is sodium stearate. Why is soap good at removing the oil from the skin? sodium stearate rule: like adheres to like. two additional factors which control intermolecular interactions (1) size The larger the molecule, the greater number of similar intermolecular interactions the molecule can have. and (2) shape. The boiling point depends upon the number of atoms on the molecule’s surface available for intermolecular interactions. determining molecular shape: ionic bonds vs. covalent bonds Determine molecular shape of: a) NF3 b) MgO c) CH3COCH3 d) TiO2 Determine molecular shape of: NF3 MgO CH3COCH3 TiO2 Mooser-Pearson What can you deduce about the molecular shape of the following ions/compounds? a) CaS b) Si c) SiF62- d) NaI3 e) HC(CH3)3 review slie 1 What are each of the types of interactions/bonds below? Na+ … Cl- H3C-SiH3 …. …. H-C≅N Mg2+… O2- N≅C-H F-H ….OH2 Mg2+… OH2 - H2Te … TeH2 What interaction holds together the following pairs of molecules? What is roughly the energy of interaction in kJ/mole? a) b) two NF3 molecules two BiF3 molecules c) two F2 molecules d) two HF molecules e) an H2O molecule and an HF molecule f) two CH4 molecules review slie 2 What can you deduce about the molecular shape of the following ions/compounds? a) CaS b) Si c) SiF62- d) NaI3 e) HC(CH3)3 review slie 3 homework Two proportionality questions a) If a series of chemically similar molecules (made from the same combination of elements) are all shaped like spheres, what is the proportionality relation between molecular mass and boiling point? b) If a series of chemically similar molecules (made from the same combination of elements) are all shaped like chains, with almost every bond on the surface of the molecule, what is the proportionality relation between molecular mass and boiling point?
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