Periodic Table

Synonyms

Periodic chart

Introduction and Definition

The modern periodic table is a schematic arrangement of all known elements, in order of increasing atomic number (i.e., number of protons in an element, its defining characteristic; Fig. 1) and hence their mass. The elegance of the periodic table is that the two-dimensional layout conveys far more than just atomic number and mass. Incorporated into the design is information about how electrons are arranged around the nucleus, the reactivities of elements, and patterns in the elements’ chemical properties. If one understands these aspects of the periodic table, it can also provide insight into how elements behave in Earth’s geochemical systems.

Periodic Table, Fig. 1

Periodic table of the elements. Atomic numbers are in the upper left corner of each element’s box; atomic weights are not shown. Group numbers are located above each column of elements. Non-metallic character increases from the bottom left of the table to the upper right;...