Insulator the band gap is large and electrons cannot make this jump Intrinsic

Insulator the band gap is large and electrons cannot

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Insulator: the band gap is large, and electrons cannot make this jump. Intrinsic semiconductor: The band gap is larger than metal but smaller than insulator unless temp is higher or certain value then they can jump. Extrinsic semiconductor: Band gap of pure material is too large for conduction, but a dopant that is either electron poor or rich is added to make a semiconductor. o Two types: o p-Type: the dopant is e- poor and adds a new set of empty bands in between fermi & conduction.
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o n-type: Dopant is electron rich and provides electron at higher level than usual fermi level. *Review types of solids from notes & Phase diagrams. Chapter 13 Solutions and their behaviors: Things to remember: Molarity (M)= Amount of SOLUTE (moles) Liters of SOLUTION (L) Molality (m)= Amount of SOLUTE (moles) Mass of SOLVENT (Kg) Weight %= Mass of SOLUTE Mass of SOLUTION x100%= Mole Fraction= Amount of Component i (moles) ࠵?࠵?࠵?࠵?࠵? ࠵?࠵?࠵?࠵?࠵?࠵? (࠵?࠵?࠵?࠵?࠵?) Solubility Equilibrium: The rate of crystallization will equal the rate of dissolution “Dynamic Equilibrium” Saturated, Unsaturated, Supersaturated: Solubility: maximum amount of material that can dissolve in a given amount of solvent at a given temperature to produce a stable solution. Saturated solution: the concentration of the solute equals its solubility *equilibrium occurs, add & goes to the bottom* Unsaturated: Concentration of solute is less than its solubility. *Can still dissolve more Supersaturated: unstable, temporarily contains a concentration of solute greater than its solubility. *more solute then can dissolve Liquids Dissolving in Liquids: Miscible: two liquids that dissolve in each other. o Ex: ethyl alcohol + water
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Immiscible: two liquids that are not soluble in each other. Forms layers o Ex: Oil + vinegar Similar Dissolves Similar: Polar solutes dissolve in polar solvents. Nonpolar solutes dissolve in nonpolar solvents. Polar solutes DO NOT dissolve in non-polar solvents. Nonpolar solutes DO NOT tend to dissolve in polar solvents. Solids dissolving in water: Follow the general rule I2 is more soluble in CCl4 than in water Salts are often more soluble in water, but there are many that do not. Enthalpy of Solution: Energy needed to separate ions o (–ΔlatticeH) endothermic Energy is evolved when the individual ions are transferred into water o (ΔhydrationH) exotheermic Overall: ΔsolnH = –ΔlatticeH + ΔhydrationH If ΔsolnH is very endothermic, then the salt will likely be insoluble.
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  • Spring '08
  • SHUMAN
  • Solubility, Chemical polarity

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