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1.25 N N : O: : .. 1.26 a) H H 01 -1 H H-C-H H-N C C H-N C C +1 O: +1 H H H O: H -1 b) The overall charge of alanine is zero. c) The oxygens are identical because of resonance. 1.27 The bonds will be polarized towards the nitrogen atom. The N atom in the ammonia molecule has a zero formal charge. In the ammonium cation the nitrogen atom carries a formal charge of plus one. This makes the N of the ammonium cation more electronegative and its hydrogens have a larger partial positive charge than the respective atoms in ammonia. 1.28 compounds normally have very high melting points. Because CaCl₂ is ionic, one would expect it to have a much higher melting point than 68°C. Therefore, it would be wise not to trust your lab partner and look it up yourself. 1.29 : Cl: The formal charge on the aluminum atom is 3 - 0 - (8/2) = -1; that on each CI atom is 7 - 6 - (2/2) = : Cl Al Cl: The shape of this anion, with 4 electron pairs (bonds) around is tetrahedral. : Cl: 1.30 In the cyanate anion the negative charge is distributed between the nitrogen and the oxygen atoms by resonance. The shape of this anion is linear. :0=C=N: : 8