* Chemical Properties: These describe how a substance interacts with other substances during chemical reactions. They involve changes in the substance's composition or structure.

* Physical Properties: These can be observed or measured without changing the substance's composition. Examples include color, density, melting point, etc.

Oxidation state describes the charge an atom would have if all its bonds were ionic. It's determined by the number of electrons gained or lost by an atom during a chemical reaction. This is clearly a chemical concept, as it directly relates to the way atoms interact and change in chemical reactions.

Example:

* Sodium (Na) has an oxidation state of +1 in NaCl. This means it loses one electron in the chemical reaction.

* Chlorine (Cl) has an oxidation state of -1 in NaCl. This means it gains one electron in the chemical reaction.

Therefore, the oxidation state of an element is a chemical property as it reflects the element's behavior in chemical reactions.