What does the atomic number of an element represent?

The atomic number of an element is a fundamental property that uniquely defines that element. It represents the number of protons found in the nucleus of an atom of that element. This is critical because the atomic number determines the identity of the element. For example, an element with an atomic number of 6 is carbon, as it has 6 protons in its nucleus.

Additionally, the atomic number is also equal to the number of electrons in a neutral atom, which is why there may be some confusion. However, the primary definition that distinguishes the atomic number is its association with protons. The other options—neutrons, mass number, and electrons—relate to different aspects of atomic structure, but they do not define what the atomic number is. Thus, understanding that the atomic number directly corresponds to the count of protons is key to grasping its significance in chemistry and physics.