A chemical property is a characteristic observed when a substance reacts with another substance.
- types of chemical bonds formed
- chemical stability
A physical property is a characteristic that can be observed using the five senses - sight, smell, touch, taste, and hearing.
- melting point
- boiling point
Chemical properties are those observed or measured during chemical changes (reactions of some sort). Physical properties can be measured without such a change.
Essentially, physical properties can be defined or measured as intrinsic properties of a substance that does not require the substance to undergo any change of chemical composition to be measured. Examples are things such as density, hardness, melt point, boiling point, colour etc.
Chemical properties can only be observed or measured when the substance undergoes a change of chemical composition, i.e. undergoes chemical reaction. Heat of combustion, heat of formation, flash point and so on. These are all chemical properties.