Biochemistry is the study of an intricate interwoven `designed' use of many elements in cells. It can only be fully appreciated in terms of the patterns of flow of chemicals, of ionic and electronic charge, and of energy directed in space. This requires a knowledge of the selection of the elements not only in analytical terms of uptake and chemical combination but also in terms of their spatial separation and functional specification. Starting from the abundance and availability of the elements an attempt is made here to analyse the roles of the elements, showing that much of the `chosen' chemistry is an inevitable consequence of atomic properties. Selection has played upon this chemistry, extracting the utmost value from it, as seen in the refinement of functions of individual elements so that each element plays a quite separate and distinct role. Unique qualities dominate comparative similarities through the use of evolved specific small molecule and protein ligands. Proteins provide the evolutionary media for the development of function. It was the recognition and separation of each element in their specific sites (proteins) that allowed elements to be positioned in space. In turn the spatial organization generates, through feedback, the flow of other elements. Biological chemistry is only understandable in terms of the symbiotic use of some 25 elements and should not be related to so-called organic rather than to so-called inorganic chemistry.