Concept explainers
When two amino acids react with each other, they form a linkage called an amide group, or a peptide link. (If more linkage. are added, a protein or polypeptide is formed.)
(a) What are the hybridizations of the C and N atoms in the peptide linkage?
(b) Is the structure illustrated the only resonance structure possible for the peptide linkage? If another resonance structure is possible. compare it with the o ne shown. Decide which is the more important structure.
(c) The computer-generated structure shown here, which contains a peptide linkage, shows that this linkage is flat. This is an important feature of proteins. Speculate on reasons that the CO—NH linkage is planar. What are the sites of positive and negative charge in this dipeptide?
Want to see the full answer?
Check out a sample textbook solutionChapter 9 Solutions
Chemistry & Chemical Reactivity
- 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?arrow_forward7. Nitrogen is the central atom in each of the species given. (a) Draw the Lewis electron-dot structure for each of the species. + NO₂ NO₂ NO₂ (b) List the species in order of increasing bond angle. Justify your answer. (c) For NO₂ and NO₂, give the hybridization of the nitrogen atom in it. (d) Identify the only one of the species that dimerizes and explain what causes it to do so.arrow_forwardThe structure of caffeine is shown below. (a) Complete the Lewis structure. (b) How many pi bonds are present in caffeine? How many sigma bonds? (c) Identify the hybridization of the carbon atoms. (d) What is the value of the O-C-N angle?arrow_forward
- Propylene, C3H6, is a gas that is used to form the importantpolymer called polypropylene. Its Lewis structure is given. (a) What is the total number of valence electrons in the propylenemolecule? (b) How many valence electrons are usedto make σ bonds in the molecule? (c) How many valenceelectrons are used to make π bonds in the molecule? (d) Howmany valence electrons remain in nonbonding pairs in themolecule? (e) What is the hybridization at each carbon atomin the molecule?arrow_forward(a) What is the physical basis for the VSEPR model?(b) When applying the VSEPR model, we count a double ortriple bond as a single electron domain. Why is this justified?arrow_forwardPropylene, C3H6, is a gas that is used to form the importantpolymer called polypropylene. Its Lewis structure is (a) What is the total number of valence electrons in the propylenemolecule? (b) How many valence electrons are usedto make s bonds in the molecule? (c) How many valenceelectrons are used to make p bonds in the molecule? (d) Howmany valence electrons remain in nonbonding pairs in themolecule? (e) What is the hybridization at each carbon atomin the molecule?arrow_forward
- The structural formulas for ethanol, CH3CH2OH, and propene, CH;CH=CH,2, are нн H Н—С—С—0—н H-C-C=C-H нн H H H Ethanol Propene (a) Complete the Lewis structure for each molecule showing all valence electrons. (b) Using the VSEPR model, predict all bond angles in each molecule.arrow_forward10. Each ball-and-stick model below shows the electron-pair and molecular geometry of a generic molecule. Explain what is wrong with each molecular geometry and provide the correct molecular geometry based on the number of lone and bonding pairs around the central atom. (a) (b) (c) 11. Draw the Lewis structure for acetamide (CH3CONH2) and determine the geometry about each interior atom. Experiments show that the geometry about the N atom in acetamide is nearly planar. Draw a resonance structure that can account for the planar geometry about the N atom.arrow_forward(a) How does a polar molecule differ from a nonpolar one? (b) Atoms X and Y have different electronegativities. Will the diatomic molecule X—Y necessarily be polar? Explain. (c) What factors affect the size of the dipole moment of a diatomic molecule?arrow_forward
- 2. Consider the following molecules or ions: CIOF5, NOBr, NH2F, and XeO2F3+. Answer the following questions based on the Lewis structures and VSEPR theory prediction of their molecular shapes. (a) Which one has only bond angles of 109.5°? (b) Which one has only bond angles of 120°? (c) Which one has bond angles of 90 and 180°? (d) Which one has bond angles of 90, 120, and 180°?arrow_forward(b) The Murchison meteorite that landed in Australia in 1969 contained 92 different amino acids, including 21 found in Earth organism A skeleton structure (single bond only) of one of these extraterrestrial amino acids is shown below. Draw a Lewis structure, and identify any atoms having a nonzero formal charge. H3N. C ČH2 ČH3 (c) Draw the orbital diagrams and Lewis symbols to depict the formation of Na* and CI ions from the atoms. Give the formula of the compound formed. (d) The predicted bond length for HF is 109 pm (the sum of the covalent radii of H, 37 pm and F, 72 pm), however the actual bond length for HF is shorter (92 pm). It was observed that the difference between predicted and actual bond lengths becomes smaller going down the halogen group from HF to HI Describe these observationsarrow_forwardSodium azide is a shock-sensitive compound that releases N2upon physical impact. The compound is used in automobileairbags. The azide ion is N3-. (a) Draw the Lewis structure of theazide ion that minimizes formal charge (it does not form a triangle).Is it linear or bent? (b) State the hybridization of the centralN atom in the azide ion. (c) How many σ bonds and how manyπ bonds does the central nitrogen atom make in the azide ion?arrow_forward
- Chemistry & Chemical ReactivityChemistryISBN:9781337399074Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage LearningChemistry & Chemical ReactivityChemistryISBN:9781133949640Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage LearningChemistry: Principles and ReactionsChemistryISBN:9781305079373Author:William L. Masterton, Cecile N. HurleyPublisher:Cengage Learning
- Chemistry for Engineering StudentsChemistryISBN:9781337398909Author:Lawrence S. Brown, Tom HolmePublisher:Cengage Learning