How does atomic structure create insulators and conductors within matter?
it purely depends on the arrangement of electrons within the energy levels. different elements have different atomic structures making some insulators others conductors.
in the case of metals they have a metallic structure which means they have delocalised electrons which transmit electric charge. they are any group one or two elements. others like carbon have a covalent structure which means they use all their electrons in bonding making them good insulators since they can not transmit any electric charge.