new index atom name original index 1 C 4 2 C 5 3 C 6 4 C 7 5 C 8 6 C 9 7 N 3 8 O 1 9 O 2 10 H 10 11 H 11 12 H 12 13 H 13 14 H 14 15 H 15 16 H 16 17 H 17 18 H 18 19 H 19 20 H 20 21 H 21 22 H 22