In the current understanding of atomic structure, the atomic number represents the number of protons in the nucleus of an atom, which is always a whole number for known elements. The atomic number determines the identity of an element, and it corresponds to unique properties and characteristics exhibited by that element.
However, if we were to imagine an element with a fractional atomic number like 2/3, it would not align with the current model of atomic structure and would not correspond to any known element.
The properties of an element are largely determined by its atomic number, which affects its electronic configuration, chemical reactivity, and other characteristics. Since a fractional atomic number does not fit within the established framework of atomic structure, it is challenging to speculate on the theoretical properties of such an element.
In hypothetical scenarios where atomic structure is significantly different from what is currently understood, the properties of elements might vary considerably. Nonetheless, it's important to note that the concept of fractional atomic numbers does not currently have a basis in our understanding of atomic theory and the periodic table.