Substituent

Atom set which has replaced hydrogen atoms on a hydrocarbon's parent chain

In organic chemistry, a substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety in the resultant (new) molecule. The suffix -yl is used when naming organic compounds that contain a single bond replacing one hydrogen; -ylidene and -ylidyne are used with double bonds and triple bonds, respectively. In addition, when naming hydrocarbons that contain a substituent, positional numbers are used to indicate which carbon atom the substituent attaches to when such information is needed to distinguish between isomers.

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