\starttext

    \startchemical \chemical[FIVE,SB,Z]   [1,2,3,4,5] \stopchemical
    \startchemical \chemical[SIX,SB,Z]    [1,2,3,4,5,6] \stopchemical
    \startchemical \chemical[EIGHT,SB,Z]  [1,2,3,4,5,6,7,8] \stopchemical

    \startchemical \chemical[FIVE,B,R,RZ] [1,2,3,4,5] \stopchemical
    \startchemical \chemical[SIX,B,R,RZ]  [1,2,3,4,5,6] \stopchemical
    \startchemical \chemical[EIGHT,B,R,RZ][1,2,3,4,5,6,7,8] \stopchemical

\stoptext
