3.091 â Introduction to Solid State Chemistry Lecture Notes No. 2 ...

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LN–214. (a) Determine the differences in relative electronegativity (Δx in eV) for thesystems H–F and C–F given the following data:Bond EnergykJ/moleH 2 436F 2 172C–C 335H–F 565C–H 410(b) Taking X H = 2.1, determine the relative electronegativities (in eV) for C andF.15. What are the electron orbital configurations resulting from (1) sp, (2) sp 2 and(3) sp 3 hybridization?16. What types of bonds can be expected to be formed in each of the compoundslisted below, and in what “state of aggregation” (gaseous, liquid or solid) are theyencountered at room temperature?O 2 , HCl , SiO 2 , LiF , CH 417. For NaF the repulsive (Born) exponent, n, is 8.7. Making use of data given in yourPeriodic Table, attempt to calculate the crystal energy (ΔE cryst ). (What assumptiondo you have to make to calculate ΔE cryst ?)18. (a) Which atomic orbitals (discussed in class) can form σ bonds and what arethe approximate molecular orbital shapes?(b) Which atomic orbitals upon overlap cannot form π orbitals and why?19. Frequently the statement is made that the crystal energy (ΔE cryst ) ispredominantly given by the attractive energy term. How can you account for thisapproximation?20. Bringing hydrogen (H 2 ) and bromine (Br 2 ) together results in a spontaneousreaction: H 2 + Br 2 → 2HBr.(a) What do you expect the primary bonding type to be in HBr? (Give the basiccriterion for your answer.)(b) Given the bond energies E H-H = –496 kJ/mole and E Br-Br = –221 kJ/mole,what do you expect the actual bond energy to be?21. Assuming electrons do exhibit “wave properties”, what accelerating potential(voltage) must be applied to an electron so that it has a particle wavelength of0.1Å?32
LN–222. Knowing that an electron accelerated by an electrical potential of 1 Volt (V)acquires the “energy of 1eV” as kinetic energy, calculate the deBroglie wavelengthfor an electron accelerated by a potential of 15 kV.23. What is the deBroglie wavelength (λ p in m) of an electron in the M shell of atomichydrogen?24. For benzene (C 6 H 6 ), which has a schematic carbon arrangement:C CC CC C(a)(b)Determine the total number and types of covalent bonds.For each bonding type, determine the bonding orbitals which, by overlap,lead to their formation.25. Why is double bonding encountered in some carbon compounds, but not ingermanium compounds – although both exhibit sp 3 hybridization?26. One of the two compounds, NH 3 or BF 3 , is found to exhibit a permanent dipolemoment. Identify the polar species and account for the different bondingcharacteristics of the two species. (Make appropriate sketches of the respectivebonding configurations.)27. (a) Calculate (according to Pauling) the bond energy (kJ/mole) of C–Cl, given:Bond Energy (C–C): 334 kJ/moleBond Energy (Cl–Cl): 239 kJ/mole(b) What is the magnitude (%) of ionicity of the C–Cl bond?28. It takes your lecturer (weight = 174 lbs.) 2 minutes 58 seconds to get from hisoffice to 10-250. Determine his deBroglie wavelength during that stroll.29. What is the deBroglie wavelength (λ p ) of an electron in the “0” shell of atomichydrogen?30. How fast is an electron moving if it has a λ p equal to 3 times the distance it travelsin 2 seconds?31. (a) Determine the inter-ionic equilibrium distance between the sodium andchlorine ions in a sodium chloride molecule knowing that the bond energy is3.84 eV and that the repulsive exponent is 8.(b) At the equilibrium distance, how much (in percent) is the contribution to theattractive bond energy by electron shell repulsion?33
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3.091 â Introduction to Solid State Chemistry Lecture Notes No. 2 ...