Carbon exists as allotropes, which are different crystalline or molecular forms of the same substance. Graphite and diamond are allotropes of carbon. Diamond is a non-conductor whereas graphite is a good conductor because:
Correct answer: C. In graphite one of valence electron is free to move
- A. Graphite has a layered structure
- B. In graphite, all valence electrons are tetrahedrally bound
- C. In graphite one of valence electron is free to move
- D. Graphite is soft and greasy bound
Explanation
Graphite conducts electricity whereas diamond does not because in diamond the carbon atoms are bonded to other carbon atoms and all the valence electrons are bonded. whereas in graphite each carbon atom is only bonded to three other atoms. Therefore, there are delocalized (free) electrons in graphite due to 1 free valence electron in each carbon atom, which can move and carry a charge so graphite conducts electricity.
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About Electrical Properties of Solids
Electrical properties of solids depend on their band structure, charge carriers and conductivity. The topic compares conductors, insulators and semiconductors, relates resistivity to temperature, and covers intrinsic and extrinsic semiconductors, donor and acceptor impurities, electron and hole conduction, and the formation of p-type and n-type materials.
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