Molecular modelling is a fast-growing field and has been driven by significant developments in computer hardware and software in recent years. Dendrimers are hyper-branched macromolecules with well-defined geometry and high surface functionality. Dendrimers’ architecture enables control over properties such as size, shape, density, solubility, polarity, reactivity, etc. Such special features can be used to design molecules with the desired properties used for biomedical applications. The precise, quantified core–shell architectural properties and monomer shell filling characteristics of dendrimers are compared to the electron shell filling patterns of elemental atoms using the Niels Bohr periodic table. This distinction offered a basis for understanding the patterns of self-reactivity found at sub-nanoscale (atoms), lower nanoscale (dendrimers) and higher nanoscale rates involving either unsaturated electron shells, monomer shells or dendrimer shells. This chapter provides a detailed overview of macromolecular and molecular modelling of dendrimers.