* Atomic Number: The number of protons in an atom's nucleus is called its atomic number. This number is unique to each element and defines its identity. For example, all carbon atoms have 6 protons, all oxygen atoms have 8, and all gold atoms have 79.

* Chemical Behavior: The number of protons determines the element's electron configuration, which in turn dictates its chemical behavior. The electrons are responsible for bonding and reactivity, and their arrangement is directly influenced by the number of protons.

* Isotopes: While the number of neutrons can vary (creating isotopes), the number of protons always remains constant for a given element. This ensures that all atoms of a particular element have the same chemical properties.

Electrons are important for chemical reactions and bonding, but they can change in number (through ionization). The number of electrons in an atom can fluctuate depending on the atom's state.

In summary, the number of protons is the defining characteristic of an element and determines its fundamental properties. While electrons are essential for chemical interactions, their number can vary, so they don't definitively identify the element.