1.5 Conductive and Insulating Materials

1.5 Conductive and Insulating Materials

Depending on the structure of their atoms, materials can be conductors or insulators. All phenomena related to electrical conduction take place at the outer edge of the crust and between atoms.

Conductors are substances whose final layer contains one or two electrons in an incomplete orbit. The atomic structure of good conductors usually contains only one electron in the outermost shell of the atom. This is called the valence electron, and it is easily released from the atom, allowing current to flow.

Question Then, when a material is more conductive? We say that a piece of material is more conductive the freer electrons it has and the less they are bound to the nucleus (far orbitals). The most conductive materials are metals. Among them, the best conductors are silver, copper, gold and aluminum, in that order. Conductive materials allow electrons to easily flow through them. In this case, if we apply an electric force to them, a flow of electrons is established and we call it electric current. Different elements have different characteristics of electrical conductivity as well as electrical resistance (Table 1.1).

Table 1.1 Electrical conductivity and resistivity

On the other hand, we call insulators to materials that are made up of atoms with complete outer shells or missing one or two electrons. In these materials, the atoms hold on tightly to their electrons, which have little mobility. This makes it difficult for the electron to move through the atoms.

Question Which materials are good insulators? Among the insulators, we highlight: glass, porcelain, and mica, silk, Sulphur, dry air, etc., which do not have such free electrons.

Question What happens when we apply very large electrical forces to insulators? When very large electrical forces are applied, an electric current can be obtained through the piece of material. This is because its atomic structure is broken, and it is the reason why there are no perfect insulators.