What is the significance of the atomic number in the periodic table?

The atomic number is a fundamental property of an element and directly indicates the number of protons present in the nucleus of each atom of that element. This number is unique for each chemical element and determines its identity; for example, an atom with an atomic number of 6 is carbon, while one with an atomic number of 8 is oxygen. The atomic number also has implications for the atom's electron configuration, which in turn affects its chemical behavior and placement in the periodic table.

Understanding the atomic number is crucial for interpreting the properties of elements and their behavior in chemical reactions, where it fundamentally influences their reactivity, bonding, and the formation of compounds. It serves as the organizing principle for the periodic table, allowing chemists to predict how elements will interact with one another.