A ring that contains at least one heteroatom (an atom other than carbon) is called a heterocycle, and a substance based on a heterocyclic ring is a heterocyclic compound. Heterocyclic compounds containing N, O or S are by far the most common
Compounds were classified as being either aliphatic or aromatic in the latter part of the nineteenth century. To be classified as aliphatic meant then that the chemical behavior of a compound was “fatlike”. To be classified as aromatic meant then that the compound had a low hydrogen/carbon ratio and that it was “fragrant
1.12A The Structure of Methane sp3 Hybridization The 4 sp3 orbitals should be oriented at angles of 109.5° with respect to each other. An sp3-Hybridized carbon gives a tetrahedral structure for methane, and with four equivalent C—H bonds