4.1: The Periodic Table The chemical elements are arranged in a chart called the periodic table. Some characteristics of the elements are related to their position on the periodic table. 4.2: Some Characteristics of Different Groups The periodic table is useful for understanding atomic properties that show periodic trends. Periodic trends are specific patterns that are present in the periodic table that illustrate different aspects of a certain element, including its size and its electronic properties. Periodic trends, arising from the arrangement of the periodic table, provide chemists with an invaluable tool to quickly predict an element's properties. 4.3: Electronic Structure of Atoms Electrons in atoms have quantized energies. The state of electrons in atoms is described by four quantum numbers. Electrons are organized into shells and subshells about the nucleus of an atom. 4.4: Electron Configurations There are a set of general rules that are used to figure out the electron configuration of an atomic species: Aufbau Principle, Hund's Rule and the Pauli-Exclusion Principle. 4.5: Electron Configurations and the Periodic Table The arrangement of electrons in atoms is responsible for the shape of the periodic table. Electron configurations can be predicted by the position of an atom on the periodic table 4.6: Electron-Dot Symbols A Lewis electron dot diagram (or electron dot diagram or a Lewis diagram or a Lewis structure) is a representation of the valence electrons of an atom that uses dots around the symbol of the element. 4.7: Electron Arrangments (Worksheet)