numbering of each yl prefix, even at position 1 (except for -ylidyne, which as a triple bond must terminate the substituent carbon chain). Pentan-1-yl is an example of a name by this method, and is synonymous with pentyl from the previous guideline.

Note that some popular terms such as "vinyl" (when used to mean "polyvinyl") represent only a portion of the full chemical name.

Methane substituents

According to the above rules, a carbon atom in a molecule,

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