E1.1: a) The atomic number of P (phosphorus) is 15, meaning there are 15 protons. The mass number for the 31 P isotope is 31, so: 15 protons + 16 neutrons = mass number 31 (recall that mass number is number of protons and neutrons). (for parts b-d, use the same reasoning as above) b) 15 protons + 17 neutrons = mass number 32 c) 17 protons + 20 neutrons = mass number 37 d) 1 proton + 2 neutrons = mass number 3 e) 6 protons + 8 neutrons = mass number 14 E1.2: a) 1 s 2 2 s 2 2 p 3 b) 1 s 2 2 s 2 2 p 4 c) 1 s 2 2s 2 2 p 5 d) 1 s 2 2s 2 2 p 6 3 s 2 e) 1 s 2 2s 2 2 p 6 (same as Neon atom) f) 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 1 g) 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 (same as Argon atom) h) 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 (same as Argon atom) i) 1 s 2 2 s 2 2 p 6 3 s 2 3 p 4 j) 1 s 2 (same as Helium atom) k) 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 (same as Argon atom) E1.3: E1.4: E1.6: Below are full structural drawings, showing all carbons and hydrogens: E1.8: E1.10: There is only one constitutional isomer of ethanol: dimethyl ether CH 3 OCH 3 E1.11: E1.12: a) carboxylate, sulfide, aromatic, two amide groups (one of which is cyclic) b) tertiary alcohol, thioester c) carboxylate, ketone d) ether, primary amine, alkene E1.14: acetic acid: ethanoic acid chloroform: trichloromethane acetone: propanone (not 2-propanone, because the '2' in this case would be redundant: if the carbonyl carbon were not in the #2 position, the compound would be an aldehyde not a ketone) E1.17: The linking group is a phosphate diester