The proton number and the atomic number of an atom are closely related. In fact, they refer to the same fundamental property of an atom.
The atomic number of an atom is denoted by the symbol "Z" and represents the number of protons found in the nucleus of an atom. It is a unique identifier for each element on the periodic table. For example, hydrogen has an atomic number of 1, indicating that it has one proton in its nucleus. Carbon has an atomic number of 6, indicating that it has six protons in its nucleus.
The atomic number determines the identity of the element because different elements have different numbers of protons. For instance, if an atom has eight protons, it will always be oxygen, regardless of the number of neutrons or electrons it possesses.
In summary, the atomic number (Z) of an atom corresponds directly to the number of protons in its nucleus, establishing the identity of the element.