No, an atom with an atomic number of 0 is not possible. The atomic number of an atom represents the number of protons in its nucleus. Protons are positively charged subatomic particles, and every atom must have at least one proton to be considered an atom.
Atoms with atomic numbers of 0 do not exist in nature. Such an atom would not have any protons, and without protons, it would not have a positive charge to balance the negative charge of its electrons. Therefore, an atom with an atomic number of 0 would lack a nucleus and electrons, rendering it fundamentally different from any known chemical element.
In summary, an atomic number of 0 is not valid for an atom because it implies the absence of protons, which are essential for defining an atom and determining its chemical properties.