Question

Does shininess of a metal depend upon its density ?

Answer 1

Shininess of a metal does not depends upon its density. Metals are shiny because they have a lot of free (i.e. delocalized) electrons that form a cloud of highly mobile negatively charged electrons on and beneath the smooth metal surface in the ideal case. To simplify the discussion, we can think of these electrons as a negatively charged cloud in a uniform background of positive charge, forming a highly polarizable plasma. A plasma is just a dense gas of charged particles and the distribution of the charges within its volume can be changed by applying an external electromagnetic (EM) field. In the absence of any external EM field, the charges in the plasma are uniformly distributed within the metal. So, there are no regions within the metal that are more negatively charged than the other.