(a) Describe the molecule xenon trioxide, XeO3, using four possible Lewis structures, one each with zero, one, two, or three Xe—O double bonds. (b) Do any of these resonance structures satisfy the octet rule for every atom in the molecule? (c) Do any of the four Lewis structures have multiple resonance structures? If so, how many resonance structures do you find? (d) Which of the Lewis structures in (a) yields the most favorable formal charges for the molecule?  

Draw the Lewis structure with lowest formal charges, and determine the charge of each atom in (a) OCS; (b) NO. (C)CN−; (d) ClO−.

Write Lewis dot symbols for (a) Ca2+, (b) N3−, and (c) I −.

Like several other bonds, carbon-oxygen bonds havelengths and strengths that depend on the bond order. Draw Lewis structures for the following species, and arrange them in order of increasing carbon-oxygen bond length and then by increasing carbon-oxygen bond strength: (a) CO; (b) CO₃²⁻; (c) H₂CO;(d) CH₄O; (e) HCO₃(H attached to O).

8D.4. Benzene, a common solvent, is a covalent molecular compound which contains only carbon and hydrogen. Its simplest (empirical) formula is CH, and its molecular weight is 78 g/mol to 2 significant digits. What is its molecular formula? 8D.5. Draw the Lewis Dot Structure of (a) phosphorus pentafluoride. What is the formal charge on all atoms? (b) the perchlorate ion- in this case expand the octet for the chlorine atom in order to optimize the formal charges.

Keeping in mind that some elements violate the octet rule, draw a Lewis structure for each compound: (a) BCl 3; (b) SO 3.

Calculate the enthalpy change for the following reactions using the bond enthalpy given below. (Bond enthalpy/kJ : H−H = 436, C−H = 413, C=O = 799, O=O = 495, O−H = 463) (a)  H2(g) + 1⁄2O2(g) → H2O(g) (b)  CH4(g) + 2O2(g) → CO2(g) + 2H2O(l)

Acetylene (C2H2) and nitrogen (N2) both contain a triplebond, but they differ greatly in their chemical properties.(a) Write the Lewis structures for the two substances. (b) By referring to Appendix C, look up the enthalpies of formationof acetylene and nitrogen. Which compound is more stable?(c) Write balanced chemical equations for the completeoxidation of N2 to form N2O5(g) and of acetylene to formCO2(g) and H2O(g). (d) Calculate the enthalpy of oxidationper mole for N2 and for C2H2 (the enthalpy of formationof N2O5(g) is 11.30 kJ/mol). (e) Both N2 and C2H2 possesstriple bonds with quite high bond enthalpies (Table 8.3).Calculate the enthalpy of hydrogenation per mole for bothcompounds: acetylene plus H2 to make methane, CH4;nitrogen plus H2 to make ammonia, NH3.

Write a Lewis structure for the amide ion, NH2─, and assign formal charges to each atom.