The number of protons in the nucleus of an atom determines its atomic number and, therefore, its identity as an element. Each element on the periodic table has a unique number of protons, which distinguishes it from other elements. So, if an atom lacks protons in its nucleus, it would not be considered an element because it would not have a specific atomic number associated with any known element.
Neutrons, on the other hand, are not essential for defining the identity of an element. They contribute to the mass of an atom and influence its stability but do not determine its elemental identity. Isotopes of an element can have different numbers of neutrons while maintaining the same number of protons and, thus, the same element. For example, carbon-12, carbon-13, and carbon-14 are all isotopes of carbon, with different numbers of neutrons but the same number of protons.
In summary, an atom without protons in its nucleus would not be categorized as an element, while an atom without neutrons in its nucleus could still be considered an element as long as it retains its characteristic number of protons.