Functional groups, organic with single bonds

In Organic I you probably started with the hydroccirbons, compounds of carbon and hydrogen, including the alkenes and alkynes that contained double and single bonds, respectively. Then you probably touched on some of the more common functional groups, such as alcohols and maybe even some aromatic compounds. 

Most chemists still tend to think about the structure and reactivity of atomic and molecular species in qualitative terms that are related to electron pairs and to unpaired electrons. Concepts utilizing these terms such as, for example, the Lewis theory of valence, have had and still have a considerable impact on many areas of chemistry. They are particularly useful when it is necessary to highlight the qualitative similarities between the structure and reactivity of molecules containing identical functional groups, or within a homologous series. Many organic chemistry textbooks continue to use full and half-arrows to indicate the supposed movement of electron pairs or single electrons in the description of reaction mechanisms. Such concepts are closely related to classical valence-bond (VB) theory which, however, is unable to compete with advanced molecular orbital (MO) approaches in the accurate calculation of the quantitative features of the potential surface associated with a chemical reaction. 

Skeletal formula The representation of an organic compound s carbon-to-carbon bonds by lines. A single line represents a single bond with double and triple lines for double and triple bonds, respectively. The carbon-to-hydrogen bonds are assumed but not shown apart from the outline, but other functional groups or elements use their conventional representation. 

A complete dichotomy between bond order and other functionality. This is in contrast to IUPAC s organic nomenclature, which uses morphemic suffixes to specify both degree of bond unsaturation (ane, -ene, and -yne), and also selected functional groups (-one, -al, etc.). In the proposed system, on the other hand, the individual chemical symbols for atoms alternate with bond descriptors (small integers or selected symbols). In particular, traditional single, double and triple bonds are... 

---