Final answer:
Metals have lower binding energy allowing for free movement of electrons, making them good conductors. Insulators have higher binding energy which prevents the easy flow of electrons, thus they are poor conductors.
Step-by-step explanation:
Materials such as metals and insulators have differing abilities to conduct electricity due to the behavior of their electrons when subjected to an electric field. Metals have a lower binding energy (BE), which allows the free electrons to move more easily among the atoms. This movement of electrons is what makes metals good conductors of electricity. The free electrons in a metallic lattice structure can move freely in a 'sea' of electrons, becoming delocalized from individual atoms which facilitates conduction.
In contrast, insulators, which are typically nonmetals, have a higher binding energy, holding their electrons more tightly to the atoms and thus inhibiting the flow of charge. As a result, insulators are not conducive to electron flow and thus do not conduct electricity well. If excess charge is added to an insulator, it usually remains stationary and does not flow through the material, maintaining electric forces for long periods.
In summary, metals have lower BE, making it easier for electrons to move and thus facilitating electric conduction, making them good conductors. Meanwhile, insulators have higher BE, making it difficult for electrons to move, inhibiting charge flow and making them poor conductors of electricity.