Page 7 - Curriculum Visions Dynamic Book

(Above and below) The structure of graphite produces a soft, slippery material. Graphite is used for pencil leads and as a lubricant.
(Above and right)
A ceramic used as an insulator
to separate high- voltage electricity wires from the steel tower that supports them.
In some ceramics the metal ions, which are normally centrally placed among all of their surrounding oxygen ions, can be made to move closer to some of the oxygen ions and thus farther from others. This has the effect of making the material able to hold enormous electrical charges. Ceramics of this kind are used as electrical storage devices called capacitors.
Of course, ceramics are normally thought of as insulators, that is, materials that do not conduct electricity, or at best conduct it very poorly. To understand this property, it is best to compare them with metals, which are good conductors of electricity. In a metal the atoms share many of their electrons, so that electrons can easily move around. The movement of electrons produces an electric current. In ceramics the electrons cannot move around in this way, and so the materials are insulators.
See Vol. 2: Metals for more on metals and conductivity.
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