Atomic structure. Conceptual computer artwork of the structure of an atom. In the center of the atom is the nucleus, made up of a tightly packed cluster of protons and neutrons. Electrons (blue, four seen here) orbit around the nucleus. This classical atomic model is known as the Bohr Model, after the Danish physicist Neils Bohr. However, in modern quantum physics it has proved impossible to precisely locate the position of atomic electrons. Instead they are represented by fuzzy clouds, large areas within which there is a high probability of an electron being found.