In IUPAC nomenclature, what does the prefix "cyclo-" indicate?

The prefix "cyclo-" in IUPAC nomenclature indicates that the compound is a cyclic or ring structure. This prefix is used to denote that the carbon atoms in the molecule are arranged in a closed loop or ring formation, which is a distinct structural feature compared to linear or branched compounds. Cycloalkanes, for example, are saturated hydrocarbons that form rings and include the simplest members like cyclopropane, cyclobutane, and so forth.

Understanding this means recognizing the unique characteristics of cyclic compounds, which can greatly impact their chemical properties and reactivity compared to linear or branched structures. Being familiar with these terms is essential in organic chemistry, particularly in the systematic naming of compounds.