A tabular arrangement of all known chemical elements, organized by increasing atomic number, electron configuration, and recurring chemical properties. Elements in the same column (group) typically share similar behaviors (e.g., noble gases are all inert). The table is a powerful predictive tool; its layout allowed scientists to predict the existence and properties of elements that hadn't been discovered yet.
Created by Russian chemist Dmitri Mendeleev in 1869.
The universal framework for understanding chemistry, found in every science classroom worldwide.