Chemical compounds of biogenic elements are considered (i.e., chemical elements present in living organisms and ensuring the successful functioning of their various organs and systems). Biogenic elements are divided into s-, p-, and d-elements, in which respectively are completed with s-, p-, and d-electronic orbitals. In each of these groups, the structure of compounds of biogenic elements is investigated, and the dimension of the corresponding molecules is determined. It is proved that s- and d-biogenic elements exhibit increased chemical activity (higher than the standard valence) due to participation in the formation of a chemical bond of electrons of the preceding level. This leads to the creation of complex molecules of higher dimension. The chemical compounds of biogenic p-elements, which are the building blocks for the formation of biomolecules (elements of life), will be specifically investigated in subsequent chapters.