What does the atomic number tell us about an atom?

The atomic number is a fundamental characteristic of an element that indicates the number of protons present in the nucleus of an atom. This number uniquely defines the element, as each element on the periodic table has a distinct atomic number. For instance, hydrogen has an atomic number of 1, meaning it has one proton, while carbon has an atomic number of 6, indicating it has six protons.

The atomic number also has implications for the number of electrons in a neutral atom, where the number of electrons equals the number of protons. However, the atomic number itself explicitly refers to protons. Therefore, it is essential in understanding the basic identity of an element and its placement in the periodic table.