There are three possible structures for PCl2F3 with phosphorus as the central atom. Draw them and discuss how measurements of dipole moments could help distinguish among them.

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

Acetylene 1C2H22 and nitrogen 1N22 both contain a triplebond, but they differ greatly in their chemical properties.(a) Write the Lewis structures for the two substances. (b) Byreferring 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 N2O51g2 and of acetylene to formCO21g2 and H2O1g2. (d) Calculate the enthalpy of oxidationper mole for N2 and for C2H2 (the enthalpy of formationof N2O51g2 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.

Chloral, Cl3C—CH=O, reacts with water to form the sedative and hypnotic agent chloral hydrate, Cl3C—CH(OH)2. Draw Lewis structures for these substances, and describe the change in molecular shape, if any, that occurs around each of the carbon atoms during the reaction.

. Assume that the third-period element phosphorus forms a diatomic molecule, P2, in an analogous way as nitrogen does to form N2. (a) Write the electronic configuration for P2. Use [Ne2] to represent the electron configuration for the first two periods. (b) Calculate its bond order. (c) What are its magnetic properties (diamagnetic or paramagnetic)?

Carbon, nitrogen, and oxygen form two different polyatomic ions: cyanate ion (NCO) and fulminate ion (CNO). Write Lewis structures for each anion, including near-equivalent resonance structures (do not add any arrows between structures) and indicating formal charges. The isocyanate ion also has two near-equivalent structures, but the formal charge on the nitrogen attom cannot be reduced to zero: Cyanate ion (NCO)

Nitrogen trifluoride (NF3) is used in the electronics industry to clean surfaces. NF3 is also a potent greenhouse gas. (A) Draw the Lewis structure of NF3 and determine its molecular geometry. (B) BF3 and NF3 both have three covalently bonded fluorine atoms around a central atom. Do they have the same dipole moment? (C) Could BF3 also behave as a greenhouse gas? Explain why or why not.

Hydrogen cyanide can be catalytically reduced with hydrogen to form methylamine. Use Lewis structures and bond energies to determine ΔH°rxn for HCN(g) + 2 H2(g) ⟶ CH3NH2(g)

Formamide, HC(O)NH2, is prepared at high pressures from carbon monoxide and ammonia, and serves as an industrial solvent (the parentheses around the O indicate that it is bonded only to the carbon atom and that the carbon atom is also bonded to the H and the N atoms). Two resonance forms (one with formal charges) can be written for formamide. Write both resonance structures, and predict the bond angles about the carbon and nitrogen atoms for each resonance form. Are they the same? Describe how the experimental determination of the HNH bond angle could be used to indicate which resonance form is more important.

It is possible to write a simple Lewis structure for the SO42- ion, involving only single bonds, which follows the octet rule. However, Linus Pauling and others have suggested an alternative structure, involving double bonds, in which the sulfur atom is surrounded by six electron pairs. (a) Draw the two Lewis structures. (b) What geometries are predicted for the two structures? (c) What is the hybridization of sulfur in each case? (d) What are the formal charges of the atoms in the two structures?