As i know, the metallic structure for example a pure copper metal which is made up of all metal atoms that is the copper atoms actually have all its atom of metallic element bonded together by metallic bonding. Metallic bonding is the electrostatic force of attraction between the positively charged metal cations and the delocalized electrons that contribute to the negatively charged electrons cloud right?? (as in my picture) My Question is why electrons cloud is formed in metallic structure only instead of semiconductor and insulator ?? And when electric field due to the electrical potential difference is created across the metal, is it the delocalized electrons in the electrons sea are made to move in a specific direction and constitute an electric current ??