substituent

/səbˈstɪtʃuənt/
noun
  1. An atom or group of atoms that replaces another atom or group in a chemical compound.
    • The chemist studied how each substituent affected the compound's reactivity.
    • Adding a methyl substituent changed the color of the dye.
    • In the molecule, a chlorine substituent replaced the hydrogen atom.
Synonyms
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