What prefix is used when naming compounds containing three carbon atoms?

The prefix used when naming compounds containing three carbon atoms is "tri-". In organic chemistry, prefixes are used to indicate the number of carbon atoms in the longest continuous carbon chain of a molecule.

In this context:

• "Tri-" specifically denotes that there are three carbon atoms (C3) present. This is reflected in common prefixes used for various hydrocarbons, like "propane," which has three carbons.

• The other prefixes do not apply to three carbon atoms: "di-" refers to two carbon atoms, "penta-" indicates five carbon atoms, and "hepta-" corresponds to seven carbon atoms. Thus, these are not relevant when identifying a compound with three carbons.

Understanding the correct prefix is essential for accurate nomenclature in organic chemistry, ensuring proper communication of molecular structure and composition.