What is the atomic number of an element defined as?

The atomic number of an element is defined as the number of protons in the nucleus of an atom of that element. This number is crucial because it determines the identity of the element itself; for example, an atom with one proton is hydrogen, while an atom with six protons is carbon. The atomic number not only defines the element but also determines its position on the periodic table, which is organized by increasing atomic number. Therefore, each element has a unique atomic number that distinguishes it from all other elements.

Understanding atomic numbers is fundamental when studying elements and their properties, as they influence the chemical behavior of atoms and play a key role in forming chemical bonds.