Fundamental Principles of Organic Chemistry

Organic chemistry is the study of hydrocarbons and their derivatives, and an organic compound is a carbon compound that contains carbon-hydrogen bonds. The definition matters because it is tested: potassium cyanate, $KOCN$, contains carbon but has no carbon-hydrogen bond, so it is inorganic, while every alcohol, acid, ether and alkane in this chapter is organic. The subject has a famous beginning. Early chemists could not synthesise organic compounds in the laboratory and concluded that organic compounds could be made only by and within living things, a belief that blocked the field until Wöhler prepared urea from an inorganic salt, ammonium cyanate. Urea was the first organic compound made in the laboratory, and its synthesis showed that no vital force was needed.

Carbon earns its own subject because of two properties. The first is tetravalency: a carbon atom has four valence electrons and forms four bonds, so it can join to four different groups at once and build the branching skeletons that give organic chemistry its variety. The second is catenation, the ability of carbon to bond to itself in long chains and in rings, which no other element does to the same extent. Add carbon's readiness to form single, double and triple bonds and the result is millions of compounds built from one element, all of them obeying the same small set of naming rules.

Those compounds sort into homologous series, families that share a general formula and a functional group and differ by one $CH_2$ unit from one member to the next. The paper expects the series and their general formulas: alkanes $C_nH_{2n+2}$, alkenes $C_nH_{2n}$, alkynes $C_nH_{2n-2}$, alcohols and halogenoalkanes and amines on $C_nH_{2n+1}$, aldehydes as $RCHO$, ketones as $RCOR$, carboxylic acids as $RCOOH$, esters as $RCOOR$, and nitriles as $RCN$. Learn the pattern and a formula that looks unfamiliar resolves into its family at a glance.