Solution Manual for Organic Chemistry 7th Edition by Brown

Solution Manual for Organic Chemistry 7th Edition by Brown CHAPTER 1 Solutions to the Problems Problem 1.1 Write and compare the ground-state electron configurations for each pair of elements: (a) Carbon and silicon C (6 electrons) 1s 2 2s 2 2p 2 Si (14 electrons) 1s 2 2s 2 2p 6 3s 2 3p 2 Both carbon and silicon have four electrons in their outermost (valence) shells. (b) Oxygen and sulfur O (8 electrons) 1s 2 2s 2 2p 4 S (16 electrons) 1s 2 2s 2 2p 6 3s 2 3p 4 Both oxygen and sulfur have six electrons in their outermost (valence) shells. (c) Nitrogen and phosphorus N (7 electrons) 1s 2 2s 2 2p 3 P (15 electrons) 1s 2 2s 2 2p 6 3s 2 3p 3 Both nitrogen and phosphorus have five electrons in their outermost (valence) shells. Problem 1.2 Show how each chemical change leads to a stable octet. (a) Sulfur forms S 2- . (b) Magnesium forms Mg 2+ . S (16 electrons): 1s 2 2s 2 2p 6 3s 2 3p 4 Mg (12 electrons): 1s 2 2s 2 2p 6 3s 2 S 2- (18 electrons): 1s 2 2s 2 2p 6 3s 2 3p 6 Mg 2+ (10 electrons): 1s 2 2s 2 2p 6 Problem 1.3 Judging from their relative positions in the Periodic Table, which element in each set is more electronegative? (a) Lithium or potassium In general, electronegativity increases from left to right across a row and from bottom to top of a column in the Periodic Table. This is because electronegativity increases with increasing positive charge on the nucleus and with decreasing distance of the valence electrons from the nucleus. Lithium is closer to the top of the Periodic Table and thus more electronegative than potassium. (b) Nitrogen or phosphorus Nitrogen is closer to the top of the Periodic Table and thus more electronegative than phosphorus. (c) Carbon or silicon Carbon is closer to the top of the Periodic Table and thus more electronegative than silicon. Problem 1.4 Classify each bond as nonpolar covalent, or polar covalent, or state that ions are formed. (a) S-H (b) P-H (c) C-F (d) C-Cl Recall that bonds formed from atoms with an electronegativity difference of less than 0.5 are considered nonpolar covalent and with an electronegativity difference of 0.5 or above are considered a polar covalent bond. Difference in Bond electronegativity Type of bond S-H 2.5 - 2.1 = 0.4 Nonpolar covalent P-H 2.1 - 2.1 = 0 Nonpolar covalent C-F 4.0 - 2.5 = 1.5 Polar covalent C-Cl 3.0 - 2.5 = 0.5 Polar covalent Problem 1.5 Using the symbols δ- and δ+, indicate the direction of polarity in each polar covalent bond. (a) C-N (b) N-O δ+ δ- δ+ δ- C-N N-O Nitrogen is more electronegative than carbon Oxygen is more electronegative than nitrogen (c) C-Cl δ+ δ- C-Cl Chlorine is more electronegative than carbon Problem 1.6 Draw Lewis structures, showing all valence electrons, for these molecules. (a) C 2 H 6 (b) CS 2 (c) HCN H H H C H C H H S C S H C N Problem 1.7 Draw Lewis structures for these ions, and show which atom in each bears the formal charge. (a) CH 3 NH 3 + (b) CO 3 2- (c) HO Methylammonium ion Carbonate ion Hydroxide ion H H O H C N + H O C O O H H H Problem 1.8 Draw Lewis structures and condensed structural formulas for the four alcohols with molecular formula C 4 H 1 0 O. Classify each alcohol as primary, secondary, or tertiary. H H H H C C C H H H H C O H H H H H C C H H C H H C O H H H H H H H H O H C C C C H H H H H OH H H O H C C C H H H H C H H OH CH 3 CH 2 CH 2 CH 2 OH CH 3 CHCH 2 OH CH 3 CH 2 CHCH 3 CH 3 C CH 3 CH 3 CH 3 Primary Primary Secondary Tertiary Problem 1.9 Draw structural formulas for the three secondary amines with molecular formula C 4 H 1 1 N. H H H H H H H H H H H H H H H C C N C C H H C N C C C H H C N C C H H H H H H H H H H H C H H H Problem 1.10 Draw condensed structural formulas for the three ketones with molecular formula C 5 H 1 0 O. O CH 3 CH 2 CH 2 CCH 3 O CH 3 CHCCH 3 CH 3 O CH 3 CH 2 CCH 2 CH 3