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Effective nuclear charge the portion of the nuclear charge that is experienced by the highest energy level electrons
Effusion the flow of a gas through a hole of dimensions small in comparison with the distance between molecules
Elastomer a material that recovers its shape after a deforming force is removed
Electrical conductivity the ability to conduct an electric current
Electrochemistry the study of the interchange of chemical and electrical energy
Electrode potential the driving force of a voltaic half-cell
Electrolysis the passage of an electric current through a substance in order to cause a chemical change; the use of electric energy to produce an oxidation-reduction process
Electrolyte a substance that dissolves or melts to form ions so that the resulting liquid is capable of conducting an electrical current
Electrolytic cell a cell in which external electric energy causes an oxidation-reduction reaction to occur
Electromagnetic energy radiant energy; waves propagated by periodic variations of electric and magnetic field energy
Electromagnetic radiation radiant energy that exhibits wavelike behavior and travels through space at the speed of light
Electron a negatively charged particle that moves around the nucleus of an atom
Electron affinity the energy change associated with the addition of an electron to a gaseous atom
Electron capture a process in which one of the inner-orbital electrons in an atom is captured by the nucleus
Electron sea model a model for metals postulating a regular array of cation sin a "sea" of electrons
Electron spin quantum number a quantum number representing one of the two possible values for the electron spin; either -1/2 or 1/2.
Electronic spectra absorption spectra resulting from the excitation of molecules between electronic energy states; ultraviolet and visible spectra
Electronegativity the relative ability of an atom to attract electrons to itself from a chemical bond
Electrophoresis the migration of colloidal particles in an electric field by virtue of their charge
Element a substance that cannot be decomposed into simpler substances by chemical or physical means
Elementary process the individual steps of a reaction mechanism
Elementary step a reaction whose rate law can be written from its molecularity
Empirical formula the simplest whole number ratio of atoms in a compound
Emulsifying agent a substance having both hydrophilic and hydrophobic character that acts to stabilize an emulsion
Enantiomers nonsuperimposable mirror images
Endothermic refers to a reaction where energy (as heat) flows into the system
End point the point in a titration at which the indicator changes color
Energy the capacity to do work or to cause heat flow
Enthalpy a property of a system equal to E + PV, where E is the internal energy of the system, P is the pressure, and V is the volume of the system. At constant pressure, the change in enthalpy equals the energy flow as heat
Enthalpy of fusion the energy necessary to change a solid to a liquid at the melting point
Enthalpy of solution the enthalpy change accompanying the dissolution of a solute in a solvent
Enthalpy of solvation the enthalpy change attending the association of solute particles with solvent molecules
Enthalpy of vaporization the energy required to convert a liquid to its vapor at the boiling point
Entropy a measure of the degree of disorder or randomness in a system
Enzyme large, protein-containing molecules that catalyze biochemical reactions
Equatorial bonds bonds radiating out from the center of a molecule around its equator
Equilibrium the state of a system in which opposing forces or rates are in balance so that no net change occurs
Equilibrium constant a quantitative index of the relative amounts of products and reactants present at equilibrium
Equilibrium expression the expression obtained by multiplying the product concentrations and dividing by the multiplied reactant concentrations, and dividing by the multiplied reactant concentrations, with each concentration raise to a power represented by the coefficient in the balanced reaction
Equilibrium position a particular set of equilibrium concentrations
Equivalence point the point in a titration when enough titrant has been added to react exactly with the substance in solution being titrated
Essential elements the elements known to be essential to human life
Ester an organic compound produced by the reaction between a carboxylic acid and an alcohol
Ether a compound containing an oxygen atom attached to two hydrocarbon residues
Excited state any energy state higher than the ground state
Exclusion principle no two electrons in an atom can have the same four quantum numbers
Exothermic refers to a reaction where energy (as heat) flows out of the system
Extensive property a property, such as mass or volume, that depends on the quantity of material in an object
Extrinsic semiconductor a semiconductor in which electric conduction is dependent upon the presence of an impurity

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