The atomic number of an element corresponds to the number of protons in the nucleus of its atoms. Each unique element has a unique atomic number, and it determines the element's position in the periodic table. For example, hydrogen has an atomic number of 1, indicating that it has one proton in its nucleus, while carbon has an atomic number of 6, indicating it has six protons.
On the other hand, the atomic weight or atomic mass of an element represents the average mass of all the isotopes of that element. An isotope is a variant of an element with the same number of protons but a different number of neutrons. The atomic weight takes into account the relative abundances of each isotope in nature.
Since the atomic number of an element is the same as the number of protons, it also indirectly influences the atomic weight. However, the atomic weight includes the contribution of both protons and neutrons. So, while the atomic number specifically refers to the number of protons, the atomic weight encompasses the combined mass of protons and neutrons in the atom's nucleus.