In the structure of the Periodic Table, elements are primarily organized by their __________, which influences their chemical behavior and properties.

In the Periodic Table, elements are arranged mainly by their atomic number, which is the count of protons in each atom’s nucleus. This number determines how many electrons are needed to balance the charge, shaping the element’s electron configuration. Because electron configuration dictates how atoms share, gain, or lose electrons, the atomic number strongly predicts chemical behavior and properties. For example, carbon has six protons, six electrons, and tends to form four bonds, while oxygen’s eight protons lead to two bonds. Thus, the atomic number is the key organizing principle of the table.