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24 Cards in this Set
- Front
- Back
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(Radial Cleavage) The breaking of a bond in such a way that each atom retains one of the bond's two electrons, it produces two radicals.
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Homolytic Cleavage
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(Ionic Cleavage) The breaking of a bong in such a way that one of the atoms retain both of the bond's electrons, forms two ions.
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Heterolytic Cleavage
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A strongly electrophilic species with a positively charged carbon atom having only three bonds.
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Carbocation
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A strongly nucleophilic species with a negatively charged carbon atom having only three bonds, the carbon has a nonbonding pair of electrons.
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Carbanion
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A highly reactive species with only two bonds to an uncharged carbon atom with a nonbonding pair of electrons (simplest ex. is methylene)
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Carbene
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(Potential- energy diagram) A plot of potential-energy changes as the reactants are converted to products. The vertical axis is potential energy, (usually free energy, but occasionally enthalpy). The horizontal axis is the reaction coordinate, a measure of the progress of the reaction.
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Reaction- Energy Diagram
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A molecule or a fragment of a molecule that is formed in a reaction and exists for a finite length of time before it reacts in the next step. It corresponds to a relative minimum( a low point) in the reaction- energy diagram.
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Intermediate
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A substance that increases the rate of a reaction (by lowering E_a) without being consumed in the reaction.
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Catalyst
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(Activated Complex) The state of highest energy between reactants and products. A relative maximum (high point) on the reaction-energy diagram.
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Transition State
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(Free Radical) the relationship between the concentrations of the reagents and the observed reaction rate
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Rate Equation
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A quantity calculated from the relative amounts of the products and reactants present at equilibrium.
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Equilibrium Constant
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The proportionality constant K_r in the rate equation (rate= K_r(A)_a(B)^b)
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Rate Constant
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A multistep reaction where a reactive intermediate formed in one step brings abut a second step that generates the intermediate needed for the following step
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Chain Reaction
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A reaction in which one atom replaces another, usually as a substituent on a carbon atom.
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Substitution Reaction
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The energy difference between the reactants and the transition state, the minimum energy the reactants must have for the reaction to occur.
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Activation Energy (E_a)
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The amount of enthalpy required to break a particular bond homolytically, to give radicals
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Bond- Dissociation Enthalpy (BDE)
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The slowest step in a multistep sequence of reactions (In general it is the step with the highest- energy transition state)
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Rate- Limiting Step (Rate- Determining Step)
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Related species (on a reaction-energy diagram) that are closer in the energy are also closer in structure. In an exothermic reaction, the transition state is closer to products in energy and in structure
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Hammond Postulate
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Stabilization that takes place by delocalization of electrons in a pi bonded system, Cations, radicals, and anions are often stabilized by resonance delocalization.
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Resonance Stabilization
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Giving off heat( having a negative delta H)
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Exothermic Reaction
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Consuming heat (having a positive delta H)
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Endothermic Reaction
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A measure of the reaction's tendency to go in the direction written. A decrease in it is favorable for a reaction. (Delta G= Delta H- T Delta S)
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Free Energy (Gibbs free energy; G)
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A measure of heat energy in a system. In a reaction, the heat absorbed or evolved is called the heat of reaction, Delta H. A decrease in it is favorable for a reaction.
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Enthalpy (Heat content; H)
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A measure of disorder or freedom of motion. An increase in it (Positive delta S) is favorable for a reaction.
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Entropy (S)
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