Question
Classification of solid based on conductivity
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Answer
→ Materials are classified into conductors, insulators and semiconductors depending on the magnitude of their conductivity.
→ Metals and their alloys have very high conductivity and are known as conductors.
→ Certain non-metals like carbon-black, graphite and some organic polymers* are also possess electronically conductivity.
→ Substances like glass, ceramics, etc., having very low conductivity are known as insulators.
→ Substance like silicon, doped silicon and gallium arsenide having conductivity between conductors and insulators are called semiconductors and are important electronic materials.
→ Certain material called superconductors exhibit zero resistivity or infinite conductivity.
→ Earlier, only metals and their alloys at very low temperatures (0 to 15 K) were known to behave as superconductors, but now days a number of ceramic materials and mixed oxides are also known to show superconductivity at temperatures as high as 150 K.
→ The values of Conductivity of some Selected Materials at 298.15 K are given below.
→ Metals and their alloys have very high conductivity and are known as conductors.
→ Certain non-metals like carbon-black, graphite and some organic polymers* are also possess electronically conductivity.
→ Substances like glass, ceramics, etc., having very low conductivity are known as insulators.
→ Substance like silicon, doped silicon and gallium arsenide having conductivity between conductors and insulators are called semiconductors and are important electronic materials.
→ Certain material called superconductors exhibit zero resistivity or infinite conductivity.
→ Earlier, only metals and their alloys at very low temperatures (0 to 15 K) were known to behave as superconductors, but now days a number of ceramic materials and mixed oxides are also known to show superconductivity at temperatures as high as 150 K.
→ The values of Conductivity of some Selected Materials at 298.15 K are given below.
| Material | Conductivity/S$m ^{-1}$ | Material | Conductivity/S$m ^{-1}$ |
| Conductors | Aqueous Solution | ||
| Sodium | $2.1 \times 10^3$ | Pure water | $3.5 \times 10^{-5}$ |
| Copper | $5.9 \times 10^3$ | 0.1 M HCl | 3.91 |
| Silver | $6.2 \times 10^3$ | 0.01 M KCI | 0.14 |
| Gold | $4.5 \times 10^3$ | 0.01M NaCl | 0.12 |
| Iron | $1.0 \times 10^3$ | 0.1 M HAc | 0.047 |
| Graphite | $1.2 \times 10$ | 0.01M HAc | 0.016 |
| Insulators | Semiconductors | ||
| Glass | $1.0 \times 10^{-16}$ | CuO | $1 \times 10^{-7}$ |
| Teflon | $1.0 \times 10^{-18}$ | Si | $1.5 \times 10^{-2}$ |
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Column II (Metal)
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