Some questions about dielectrics/insulators

[iScience]

Dielectrics are insulating materials that can be polarized in the presence of an external E-field, so are all insulators with the ability to distribute its charges throughout its volume considered dielectrics? What property of a dielectric/insulator allows its electrons to be redistributed throughout the material's entire volume when charge is induced on it? i thought an ideal insulator was supposed to have no free electrons (no conduction band electrons) so then this implies either...

1.) free electrons are in fact the 'stuff' getting redistributed and therefore not a perfect insulator

or...

2.) i am moving something else.. maybe...the valance electrons?




last question (important, please answer this one!): do there exist insulating materials where when i induce charge at some local site on the insulator, the charge just remains there and does not get distributed throughout the whole volume?

thanks so much guys!

 

[dauto]

The valence electron's equilibrium position changes slightly