Here's why:

* Physical properties are characteristics of a substance that can be observed or measured without changing the substance's chemical composition. Examples include color, density, melting point, and conductivity.

* Chemical properties describe how a substance reacts with other substances or how it changes its chemical composition. Examples include flammability, reactivity with acids, and oxidation.

A good conductor of heat simply means the substance allows heat to flow through it easily. This is a characteristic of the material itself and doesn't involve any chemical reactions or changes in the substance's composition.