These definitions are the preferred ones to be used in Organic Chemistry. Note that some terms (such as configuration) have more than one interpretation.
<span>acid:</span> an agent able to produce positively charged hydrogen ions (H+). [Since the hydrogen ion is a bare proton, it usually exists in a solvated form (such as H3O+).]
<span>achiral: </span>not chiral. A compound (or object) that is superimposible on its mirror image. For example CH4.
<span>activation energy:</span> the miminmum energy which reacting species must possess in order to be able to form an 'activated complex', or 'transition state', before proceeding to the products. [The activation energy (Ea) may be derived from the temperature dependence of the reaction rate using the Arrhenius equation.]
<span>addition reactions:</span> reactions in which an unsaturated system is saturated or part saturated by the addition of a molecule across the multiple bond.[E.g. the addition of bromine to ethene to form 1,2-dibromoethane]
<span>alkaloid: </span>organic substances occurring naturally, which are basic, forming salts with acids. The basic group is usually an amino function.
<span>allyl group:</span> a group containing 3 carbon atoms and a double bond [C1=C2-C3, where C3 is called the allyliuc position or allylic carbon atom].
<span>allylic rearrangement:</span> the migration of a double bond in a 3-carbon system from carbon atoms one and two to carbon atoms two and three,
<span>e.g. C1=C2-C3-X X-C1-C2=C3</span>
