By Jo Jackson | Updated Mar 24, 2022
A Bohr diagram, introduced by Danish physicist Niels Bohr in 1913, offers a clear visual of an atom’s structure. It shows a positively charged nucleus surrounded by electrons in concentric circular orbits, each orbit representing a distinct energy level. Bohr diagrams are ideal for teaching the basics of quantum mechanics, as they illustrate how electrons occupy discrete energy shells.
Refer to the Periodic Table to identify the element you wish to represent. Record its atomic number (the number of protons) and mass number (protons plus neutrons). In a neutral atom, the number of electrons equals the number of protons. Note the element’s period: elements in the first row have one energy level, those in the second row have two, and so forth.
Draw a small circle for the nucleus. Inside, write the element’s symbol and list the number of protons and neutrons. Surround this nucleus with one or more rings, each corresponding to a different energy level based on the element’s period.
Mark electrons as dots on the rings. Each energy level has a capacity: the first (inner) shell holds up to 2 electrons, the second up to 8, the third up to 18, and the fourth up to 32. Once the electrons are placed, the diagram is complete.
