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