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Berzelian Classification System (7720 words) |
 | Semimetals and nonmetals are brittle and conduct poorly compared to metals. |
| The lattices of the semimetals are composed of bonds intermediate in type between metallic and covalent. |
| The structure of the hexagonal semimetals is therefore based on a distorted form of cubic closest packing in which sheets of atoms parallel to the base of the crystal separate into pairs. |
| Bands, Bonds, and Doping (4697 words) |
| Semimetals (Figure 5), which lie between metals and nonmetals on the periodic table, have an energy gap between the valence and conduction bands (band gap) similar to nonmetals (not a continuous band like metals), but the band gap for semimetals is smaller than for nonmetals. |
| Semimetals, which occupy intermediate positions on the periodic table, have bonds of intermediate strength and directionality, and a small band gap. |
| The band gap in semimetals is small enough (recall Figure 5) that an electron can be promoted from the filled lower-energy band to the unfilled higher-energy band with a moderate input of energy (such as the thermal energy that dissipates in the solid when electrical current is passed through it). |
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