Final answer:
Argon (Ar) is a noble gas with a full valence shell and typically has an oxidation number of 0. It does not form ions under normal conditions and thus does not have a traditional oxidation number or Lewis dot diagram indicating ion formation.
Step-by-step explanation:
Since the element in question is Argon (Ar), which is a noble gas, its oxidation number is a bit of a misnomer, as noble gases typically do not form ions due to their full valence shells and thus do not have oxidation numbers in the traditional sense.
The Lewis dot diagram for Argon would simply show eight dots around the symbol for Argon, denoting its full valence shell of eight electrons. However, in an exceptional case where Argon does form an ion, it would likely be in an excited or unstable state. Noble gases have oxidation numbers of 0 because they are already in a stable configuration and do not normally gain or lose electrons.
Note: Oxidation numbers are usually written with the sign first, then the magnitude, to differentiate them from charges. But in the case of noble gases like Argon, since they are unreactive and do not typically form compounds, the oxidation number is not applicable.