1. Also called: first cousin, cousin-german or full cousin the child of one's aunt or uncle. 2. a relative who has descended from one of one's common ancestors. A person's second cousin is the child of one of his parents' first cousins. A person's third cousin is the child of one of his parents' second cousins. A first cousin once removed (or loosely second cousin) is the child of one's first cousin.
As a functional group, benzene and substituted benzenes are called arenes. Nomenclature: Functional group suffix = -benzene (review) Functional group prefix = phenyl-Substituted benzenes are usually named as such.The relative positions can be denoted as 1,2- = ortho-, 1,3- = meta-and 1,4- = para-substitution.When polysubstituted, the numbers alone are used, e.g. 1,2,3-trimethylbenzene.omenclature: Functional group suffix = -benzene (review) Functional group prefix = phenyl-Substituted benzenes are usually named as such. The relative positions can be denoted as 1,2- = ortho-, 1,3- = meta-and 1,4- = para-substitution. When polysubstituted, the numbers alone are used, e.g. 1,2,3-trimethylbenzene.
Functional groups are specific groups of atoms or bonds within molecules. They are responsible for the characteristic chemical reactions of those molecules. Functional groups are attached to the carbon backbone of organic molecules. They determine the characteristics and chemical reactivity of molecules. The same functional group undergoes the same chemical reactions regardless of the size of the molecule it is a part of. Functional groups are less stable than the carbon backbone. They are more likely to take part in chemical reactions.