1. Which of the following species has the longest N—O bond? NO3 NO+ NO2− H2NOH

Best Lewis Formula and Molecular Geometry A student writes the Lewis electron-dot formula for the carbonate anion, CO32, as a Does this Lewis formula obey the octet rule? Explain. What are the formal charges on the atoms? Try describing the bonding for this formula in valence bond terms. Do you have any difficulty doing this? b Does this Lewis formula give a reasonable description of the electron structure, or is there a better one? If there is a better Lewis formula, write it down and explain why it is better. c The same student writes the following resonance description for CO2: Is there something wrong with this description? (What would you predict as the geometries of these formulas?) d Is one or the other formula a better description? Could a value for the dipole moment help you decide? e Can you write a Lewis formula that gives an even better description of CO2? Explain your answer.

a Carbonyl fluoride, COF2, is an extremely poisonous gas used in organofluorine synthesis. Give the valence bond description of the carbonyl fluoride molecule. (Both fluorine atoms are attached to the carbon atom.) b Nitrogen, N2, makes up about 80% of the earths atmosphere. Give the valence bond description of this molecule.

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.

Answer the questions in the table below about the shape of the sulfur hexachloride (SC16) molecule. What word or two-word phrase best describes the shape of the SC16 molecule? What is the angle between the sulfur-chlorine bonds? (If there is more than one angle, pick the smallest.) X O Ś

Which of the following is false. the bond angle in water is smaller than in ammonia because the atomic radius of oxygen is bigger than the one of nitrogen. the bond angle in water is smaller than in ammonia because the O-H bond is shorter than the N-H bond. the bond angle in water is smaller than in ammonia because of the bigger number of lone pairs on the central atom.

Fill the blanks in the table below for BrF and SnF. BrF. SnF." number of electron groups around the central atom number of bonding electron groups around the central atom What is the structure of the molecule? 4 4 Is it polar or non-polar compound? Which hybrid orbital is used for the central atom?

Put the following three molecules in order of increasing H-X-H bond angle, where X is the central atom. CH4 H2S PH3 A. CH4 < H2S < PH3 B. H2S < PH3 < CH4 C. CH4 < PH3 < H2S D. H2S < CH4 < PH3 E. PH3 < CH4 < H2S く く

10. Molecular Chlorine, Oxygen and Nitrogen- Draw the Lewis dot structures and structural formulas Molecule Lewis Dot Structure Structural Formula Chlorine Отудеn Nitrogen Do these molecules have an interior atom? What is their molecular shape? How many sigma and pi bonds does each molecule have? Number of Sigma Bonds Number of PI Bonds Chlorine Охудев Nitrogen