Illustrated Glossary of Organic Chemistry

Pentavalent carbon (Texas carbon): A carbon atom with five covalent bonds. Sometimes called a Texas carbon because everything (including, apparently the valence of carbon) is "bigger in Texas". In most molecules carbon can have at most eight valence shell electrons, allowing for a maximum of four covalent bonds and/or lone pairs. Exceptions are very rare. In general pentavalent carbons are not acceptable in introductory organic chemistry.


Carbon can have at most four covalent bonds. "Starfish methane" with its pentavalent carbon is out of the question.