Q4: Draw the Lewis structures for the cyanate ion (OCN) and the fulminate ion (CNO). Draw all possible resonance structures for each. Determine which form for each is the major resonance contributor.

Write the Lewis structure for nitrosyl fluoride, FNO. Using only a periodic table, identify (a) which is the longer bond. (b) which is the stronger bond. (c) which is the more polar bond.

Bond Enthalpy When atoms of the hypothetical element X are placed together, they rapidly undergo reaction to form the X2 molecule: X(g)+X(g)X2(g) a Would you predict that this reaction is exothermic or endothermic? Explain. b Is the bond enthalpy of X2 a positive or a negative quantity? Why? c Suppose H for the reaction is 500 kJ/mol. Estimate the bond enthalpy of the X2 molecule. d Another hypothetical molecular compound, Y2(g), has a bond enthalpy of 750 kJ/mol, and the molecular compound XY(g) has a bond enthalpy of 1500 kJ/mol. Using bond enthalpy information, calculate H for the following reaction. X2(g)+Y2(g)2XY(g) e Given the following information, as well as the information previously presented, predict whether or not the hypothetical ionic compound AX is likely to form. In this compound, A forms the A+ cation, and X forms the X anion. Be sure to justify your answer. Reaction: A(g)+12X2(g)AX(s)The first ionization energy of A(g) is 400 kJ/mol. The electron affinity of X(g) is 525 kJ/mol. The lattice energy of AX(s) is 100 kJ/mol. f If you predicted that no ionic compound would form from the reaction in Part e, what minimum amount of AX(s) lattice energy might lead to compound formation?

Aspirin is made from salicylic acid, which has this Lewis structure: (a) Which is the longest carbon-carbon bond? (b) Which is the strongest carbon-oxygen bond? (c) Draw resonance structures for this molecule.

Methylcyanoacrylate is the active ingredient in super glues. Its Lewis structure is In this molecule, which is the (a) weakest carbon-containing bond? (b) strongest carbon-containing bond? (c) most polar bond?

Write all possible resonance structures for the following species. Assign a formal charge to each atom. In each case, which resonance structure is the most important? (a) NO2 (nitrogen is central) (b) ClCN

What possible error(s) exist in the Lewis structure (assume we are trying to represent the best possible Lewis structure for the NO₂S ion knowing N is the central atom in this polyatomic ion)? [:ö==S: N= CO :O: The best structure would have double bond and two lone pairs on each oxygen atom and a single bond with three lone pairs on the sulfur. There are no errors. This is the best possible structure. The Lewis structure above does not minimize formal charges, thus is the not the best possible structure. The nitrogen atom has an expanded octet, and this structure is impossible. The Lewis structure contains the wrong number of electrons, thus this structure is impossible.

The carbonate anion, CO32- , is a resonance hybrid. Draw all of the important resonance structures for this molecule. If an atom has a nonzero formal charge, be sure the formal charge is shown clearly in the structure. Use the resonance structures to calculate the average formal charge on each O atom (which are all equivalent in the "true" structure). [Note: all of the important contributing resonance structures have octets around each atom that desires an octet.]

Write all resonance structures for NCO− ion. Use formal charges to predict the most stable one (i.e. the one that has the lowest energy configuration) and the least stable. Briefly explain.

Write the Lewis structure for the NO2- ion. Include resonance structures.