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absolute zero: The temperature at which all molecular motion should cease.
accuracy: The relationship between the graduations on a measuring device and the actual standard for the quantity being measured.
acid: A substance which produces hydrogen ions in water solution (Arrhenius). A proton donor (Bronsted). An electron-pair acceptor (Lewis).
acid anhydride: An oxygen containing substance which produces an acid when dissolved in water. actinide: An element whose highest energy electron is in the 5f sublevel
activated complex: The species formed when the reactants in a chemical reaction have collided with sufficient energy to meet the activation energy requirement.
activation energy: The energy required to start chemical reaction.
activity (ion): The effective concentration of a species. addition polymerization: The formation of a polymer from monomers by an addition reaction. addition reaction: The adding on of a substance to the double bond of an alkene or the triple bond of an alkyne.
adiabatic: A process taking place without interchange of energy with its surroundings.
adsorption: The process of one substance being attracted and held to the surface of another.
alcohol: A class of organic compounds characterized by the presence of the hydroxyl group, -OH.
aldehyde: A class of organic compounds characterized by the presence of the carbonyl group (X=O) on the end carbon of the chain (RCHO).
aliphatic: A subdivision of hydrocarbons characterized by open chains and nonaromatic rings.
alkali metal: An element from group IA of the periodic table.
alkaline earth metal: An element from group IIA of the periodic table.
alkane: An aliphatic compound having only single carbon-carbon bonds.
alkene: An aliphatic compound having a double carbon-carbon bond.
alkyne: An aliphatic compound having a triple carbon-carbon bond.
alloy: A mixture of two or more metals. alpha particle: Helium nucleus.
amine: An organic compound derived from ammonia by replacement of one or more hydrogen atoms by organic radicals.
amino acid: An organic compound characterized by the presence of an amino group and a carboxylic acid group on the same carbon atom.
amorphous: A solid-appearing material without crystalline structure.
ampere: The unit of electric current equal to one coulomb per second.
amphoteric: A substance which can act as either an acid or a base.
amplitude: The displacement of a wave from the average position.
anhydrous: A substance without water of hydration.
aromatic: A group of organic ring compounds having (4n + 2) pi electrons.
asymmetric: Not symmetrical.
atomic mass: The average mass of the atoms of an element. One-twelfth the mass of the carbon-
anion: A negative ion.
anode: The positive electrode. The electrode at which oxidation occurs.
antibonding orbital: In molecular orbital theory, an orbital of the molecule which represents a higher energy than the atomic orbitals from which it was formed.
asymmetric: The property of not having symmetry.
atomic radius: The radius of an atom without regard to surrounding atoms.
atomic theory: The body of knowledge concerning the existence of atoms and their characteristic structure.
Avogadro's number: The number of objects in a mole equal to 6.02 x 1023.
Avogadro's hypothesis: The statement that equal volumes of gases at the same temperature and pressure contain the same number of molecules.
atomic number: The number of protons in the nucleus
balance: A device used to measure mass.
band: A group of extremely closely spaced energy levels occupied by free electrons in a metal crystal.
barometer: A manometer used to measure the atmospheric pressure.
baryon: A subatomic particle classified as a large hadron.
base: A substance which produces hydroxide ions in water solution (Arrhenius). A proton acceptor (Bronsted). An electron-pair donor (Lewis).
basic anhydride: An oxygen containing substance which produces a base when dissolved in water.
beta particle: An electron.
bidentate: A ligand which attaches to the central ion in two locations.
binary: A compound containing two elements.
binding energy: The energy required to split the nucleus into separate nucleons.
Bohr atom: The planetary atom.
boiling point: The temperature at which the vapor pressures of the liquid and vapor phases of a substance are equal. For an open liquid, boiling point is the temperature at which the vapor pressure equals the atmospheric pressure.
bond: OO7. Just kidding. The force holding atoms together in a compound.
bond angle: The angle between two bond axes extending from the same atom.
bond axis: The line connecting the nuclei of two bonded atoms.
bond character: The relative ionic or covalent character of a bond.
bond order: The number of electron pairs bonding two atoms as described by molecular
orbital theory: The energy required to break a bond. In molecular orbital theory, a molecular orbital which is at a lower energy level than the atomic orbitals from which it was formed.
Boyle's law: The volume of a specific amount of gas varies inversely as the pressure if the temperature remains constant.
Brownian motion: The random motion of colloidal particles due to their bombardment by the molecules of the continuous phase.
Brownian motion: The random motion of colloidal particles due to their bombardment by the molecules of the continuous phase.
buffer: A solution which can receive moderate amounts of either acid or base without significant change in its pH
bond strength: bonding orbital:
calorimeter: A device for measuring the change in enthalpy during a chemical change.
capillary rise: The tendency of a liquid to rise in a tube of small diameter due to the surface tension of the liquid.
calorimeter: A device for measuring the change in enthalpy during a chemical change.
capillary rise: The tendency of a liquid to rise in a tube of smell diameter due to the surface tension of the liquid.
carboxylic acid: A class of organic compounds containing a -COOH group.
catalyst: A substance which speeds a chemical reaction without being permanently changed itself.
catenation: The joining in chains of carbon atoms.
cathode: The negative electrode (general). The electrode at which reduction occurs (electrochemical).
cathode rays: The beam of electrons in a gas discharge tube.
cation: A positive ion.
Celsius scale: The temperature scale based on the freezing and boiling points of water.
cell potential: The voltage obtained from a voltaic cell.
cellulose: A biological polymer of glucose.
chain reaction: A reaction in which the product from each step acts as reactant for the next step.
chalcogen: An element from Group VIA of the periodic table.
Charles' law: The volume of a specific amount of gas varies directly ss the absolute temperature if the pressure remains constant.
chemical change: A change in which one or more new substances with new properties are formed.
chemical properties: The properties characteristic of a substance when it is involved in a chemical change.
chemical reaction: A chemical change.
chemistry: The study and investigation of the structure and properties of matter.
chromotography: The separation of a mixture using a technique based upon differential adsorption.
closest packing: A crystal structure particle arrangement in which the empty space between particles is minimized.
coefficient: A number placed before a formula in a balanced chemical equation to indicate the relative amount of the substance represented by the formula.
Colligative properties: Properties of solutions which depend only on the number of particles present, without regard to type.
colloid: A dispersion of particles from 1 to 100 nm in at least one dimension, in a continuous medium.
column chrometography: A chromatographic technique utilizing a glass column packed with adsorbent.
common-ion effect: An equilibrium phenomenon in which an ion common to two or more substances in a solution shifts an equilibrium away from itself.
complex ion: A central positive ion surrounded by bonded ligands.
compound: Two or more elements combined by chemical bonds.
concentrated solution: A solution in which there is high ratio between solute and solvent.
concentration: The ratio between the amount of solute and the amount of solvent in which the solute is dissolved.
condensation polymer: A polymer formed by a reaction in which a small molecule. usually water, is produced as the monomers form the polymer.
condensed state: The solid or liquid form of a substance.
conduction band: The group of extremely closely spaced energy levels in a metal which free electrons can occupy.
conductivity: A property involving the transport of electrons or heat from one point to another.
conjugate acid: The particle obtained after a base has gained a proton.
conjugate base: The particle remaining after an acid has donated a proton.
conjugated system: A series of alternating single and double bonds in an organic molecule.
contact catalyst: A catalyst which functions by adsorbing one of the reactants on its surface.
continuous phase: The dispersing medium in a colloid. control rods: Neutron absorbing materials used to control the rate of reaction in a nuclear reactor.
coordinate covalent bond: A covalent bond in which both electrons of the shared pair were donated by the same atom.
coordination number: The number of ligands surrounding the central ion.
corrosion: The gradual electrochemical destruction of a metal by substances in the environment.
coulomb: A quantity of electricity equal to 1/96 500 of a mole of electrons.
covalent bond: A bond characterized by a shared pair of electrons.
covalent radius: The radius of an atom along the bond axis.
critical pressure: The pressure needed to liquefy a gas at a critical temperature.
critical temperature: The temperature above which no amount of pressure will liquefy a gas.
crystal: A solid in which the particles are arranged in a regular, repeating pattern.
crystallization: Separating a solid from a solution by evaporating the solvent, or by cooling.
cyclic compounds: Compounds in which the atoms are bonded in a ring.
cycloalkanes: Aliphatic hydrocarbons with the carbon atoms bonded in rings.
Dalton's law: In a mixture of gases the total pressure of the mixture is the sum of the partial pressures of each component gas.
De Broglie's hypothesis: Particles may have the properties of waves.
decomposition: A reaction in which a compound breaks into two or more simpler substances.
defect: An imperfection in a crystal lattice.
degenerate: Having the same energy.
dehydrating agent: A substance which can absorb water from other substances.
deliquescence: The absorption of water from the air by a solid to form a liquid solution.
delocalized electrons: Electrons which are free to move through the electron cloud of p orbitals as in benzene.
density: Mass per unit volume.
desiccant: A dehydrating agent.
diagonal rule: A system for predicting the order of filling energy sublevels with electrons.
diffusion: The spreading of gas molecules throughout a given volume.
dipole-induced dipole force: An attraction between a dipole and a nonpolar molecule which has been induced to become a dipole.
dilute solution: A solution with a low ratio of solute to solvent.
dipole: A polar molecule.
dipole-dipole force: An attraction between dipoles.
dipole moment: The strength of a dipole expressed as charge multiplied by distance.
dislocation: A crystal defect.
dispersed phase: Colloidal particles distributed throughout the continuous phase.
dispersion force: The force between two particles due to the attraction of instantaneous separations of their charge centers.
dissociation: The separation of ions in solution.
distillation: The process of evaporating a liquid and condensing its vapor.
doping: Deliberate introduction of impurities into a crystal.
dot diagram: A pictorial representation of the location of outer level electrons in an atom, ion, or molecule. double bond:
double bond: A covalent bond in which two atoms share two pairs of electrons.
double displacement: A reaction in which the positive part of one compound combines with the negative part of another compound, and vice versa.
ductility: The property of a substance which enables it to be drawn into a fine wire.
dynamic equilibrium: An equilibrium in which two or more changes are taking place simultaneously, but at the same rate.
edge dislocation: A crystal defect in which a layer of atoms extends into the lattice between layers of unit cells.
efflorescence: The release of water molecules to the air by a hydrate.
effusion: The passage of gas molecules through small
elastic: Collisions in which kinetic energy is conserved.
electrochemistry: The study of the interaction of electric current and atoms, ions, and molecules.
electrode potential: The reduction potential in volts of a half-reaction compared to the potential of the hydrogen half-reaction at 0.0000 V.
electrolysis: A chemical change produced by an electric current.
electrolyte: A substance whose aqueous solution conducts electricity.
electrolytic cell: A cell in which an electrolysis reaction is taking place.
electron: A subatomic particle representing the unit of negative charge.
electron affinity: The attraction of an atom for an electron expressed as the energy needed to remove an electron from a negative ion to restore neutrality.
electron cloud: The space effectively occupied by an electron in an atom.
electron configuration: A description of the energy level and sublevel for all the electrons in an atom.
electronegativity: The relative attraction of an atom for a shared pair of electrons.
electrophoresis: The migration of colloidal particles under the influence of an electric field.
element: A substance whose atoms have the same number of protons in the nucleus.
elimination reaction: An organic reaction in which a small molecule is removed from a larger molecule leaving a double bond in the larger molecule.
empirical formula: The formula giving the simplest ratio between the atoms of the elements present in a compound.
endothermic: A change which takes place with the absorption of heat.
endpoint: The point in a titration where equivalent numbers of moles of reactants are present.
energy: A property of matter which may be converted to work under the proper circumstances.
energy level: A specific amount of energy or group of energies which may be possessed by electrons in an atom.
energy sublevel: A specific energy which may be possessed by an electron in an atom.
enthalpy: That part of the energy of a substance which is due to the motion of its particles.
entropy: The degree of disorder in a system.
enzyme: A biological catalyst.
equation: A shorthand representation of a chemical change using symbols and formulas.
equilibrium: A state in which no net change takes place in a system.
equilibrium constant: A mathematical expression giving the ratio of the product of the concentrations of the substances produced to the product of the concentration of the reactants for a reaction.
ester: A class of organic compounds derived by the action of an acid plus an alcohol.
esterification reaction: The production of an ester by the reaction of an alcohol with an acid.
ether: A class of organic compounds characterized by the presence of a double bonded oxygen separating two hydrocarbon radicals.
evaporation: The process by which a molecule leaves the surface of a liquid or solid and enters the gaseous state.
exclusion principle: No two electrons in an atom may have the same set of quantum numbers.
exothermic: A change which produces heat.
factor-label method: A problem solving method in which units (labels) are treated as factors.
fat: A biological ester of glycerol and a fatty acid.
fission: The splitting of a nucleus into two approximately equal parts.
fluid: A material which flows (liquid or gas).
forbidden zone: The energy gap between the outer level band and the conduction band in crystals.
formula: A combination of atomic symbols and numbers indicating the elements and their proportions in a compound.
formula mass: The sum of the atomic masses of the atoms in a formula.
formula unit: The amount of a substance represented by its formula.
fractional crystallization: The separation of a mixture into its components through differences in solubility.
fractional distillation: The separation of a mixture into its components through differences in boiling points.
fractionation: Separating a whole into its parts.
free electrons: Electrons not bound to one atom or associated with one bond.
free energy: The chemical potential energy of a substance or system.
freezing point: The temperature at which the vapor pressures of the solid and liquid are equal.
frequency: The number of complete wave cycles per unit of time.
functional isomers: Organic compounds with the same formula, but with the nonhydrocarbons part of the molecule bonded in different ways.
galvanometer: An instrument used to detect an electric current.
gamma ray: A quanta of energy of very high frequency and very small wavelength.
gas: A physical state characterized by random motion of the particles which are far apart compared to their diameters.
gas chromatography: A chromatographic method in which a carrier gas (inert) distributes the vapor being analyzed in a packed column.
geometric isomers: Compounds with the same formula but different arrangement of substituents around a double bond.
gluon: A theoretical massless particle exchanged by quarks.
glycogen: A biological polymer of glucose.
Graham's law: The ratio of the relative rates of diffusion of gases is equal to the square root of the inverse ratio of their molecular masses.
ground state: All electrons in the lowest possible energy sublevels.
group: The members of a vertical column in the periodic table.
hadrons: A class of heavy subatomic particles.
half-cell: The part of an electrochemical cell in which either the oxidation or reduction reaction is taking place.
half-life: The length of time necessary for one-half an amount of a radioactive nuclide to disintegrate.
half-reaction: The oxidation or reduction reaction in a chemical reaction.
halogen: An element from Group VIIA of the periodic table.
heat: The form of energy due to motion of particles.
heat content: Enthalpy.
heat of formation: The amount of heat produced or consumed when a mole of a compound is formed from its elements.
heat of fusion: The heat required to change 1 gram of a substance from solid to liquid.
heat of reaction: The heat produced or consumed when a chemical change takes place in the amounts indicated by the equation involved.
heat of solution: The amount of heat produced or consumed when a substance is dissolved in water. heat of vaporization: The heat needed to change 1 gram of a substance from liquid to gas.
Henry's law: The mass of a gas which will dissolve in a specific amount of a liquid varies directly with the pressure.
heterogeneous: Composed of different parts not uniformly dispersed.
homogeneous: Uniform throughout.
homologous series: A series of organic compounds which differ from each other by a specific structural unit.
hybrid orbitals: Equivalent orbitals formed from orbitals of different energies.
hydration: The adhering of water molecules to dissolved ions.
hydrate: A compound (crystalline) in which the ions are hydrated.
hydrocarbons: Compounds composed solely of carbon and hydrogen.
hydrogen bonding: An exceptionally strong type of dipole-dipole interaction due to the strong positive center in molecules in which hydrogen is bonded to a highly electronegative element.
hydrolysis: Reaction with water to form a weak acid or base.
hygoscopic: Absorbing water from the air.
ideal gas: A model in which gas molecules are treated as though they were geometric points exerting no force on each other.
ideal gas equation: PV=nRT .
idea solution: A solution obeying Raoult's law.
immiscible: Two liquids which will not dissolve in each other.
indicator: A weak organic acid whose conjugate base differs in color. Used to indicate the pH of a solution.
inertia: The tendency of an object to resist any change in its velocity.
infrared spectroscopy: A spectroscopic method useful in investigating the bonding in molecules.
inhibitor: A substance which prevents a reaction from taking place by forming a complex to tie up one of the reactants.
insulator: A substance having a large forbidden zone and which does not conduct.
intensive properties: Those properties of a substance which are independent of the amount of matter present.
interface: The area of contact between two phases.
ion: A particle with an electric charge.
ionic bond: The electrostatic attraction between ions of opposite charge.
ionic radius: The radius of an ion.
ionization constant: The equilibrium constant for the ionization of a weak electrolyte.
ionization energy: The energy required to remove an electron from an atom.
ion-product constant for water: The product of the hydronium and hydroxide ion concentrations, equal to 10-14 .
irreversible thermodynamic change: A change in volume or pressure in which some energy is lost to an entropy change.
isobaric: At constant pressure.
isomers: Two compounds having the same formula but different structures.
isomorphism: Two or more compounds having the same crystalline structure.
isothermal: At constant temperature.
isotope: Two or more atoms of an element having the same number of protons but different numbers of neutrons.
joule: The SI unit of energy equal to 1 kgm2/s2.
Joule-Thompson effect: The cooling effect achieved by allowing a highly compressed gas to expand rapidly after passing through a small opening.
kelvin: The SI unit of temperature equal to 1/273.16 the thermodynamic temperature of the triple point of water.
ketone: A class of organic compounds characterized by the presence of the carbonyl group (-C=O) between hydrocarbon radicals.
kilogram: The SI unit of mass.
kinetic energy: Energy due to motion.
kinetic theory: The group of ideas treating the interaction of matter and heat.
lanthanide: An element whose highest energy electron is in the 4f sublevel.
law of conservation of energy: Energy is conserved in all changes except nuclear reactions.
law of conservation of mass: Mass is conserved in all changes except nuclear reactions.
law of conservation of mass and energy: The total amount of mass and energy in the universe is constant.
law of definite proportions: The elements composing a compound are always present in the same proportions by mass.
law of multiple proportions: The masses of one element which combine with a specific mass of another element in a series of compounds. These masses are in the ratio of small whole numbers.
Le Chatelier's principle: If a stress is placed on a system at equilibrium, the system will shift so as to offset the stress.
leptons: A class of light subatomic particles.
ligand: A negative ion or polar molecule attached to a central ion in a complex.
limiting reactant: The reactant which is used completely in a reaction.
linear accelerator: A device for imparting a high energy to atomic or subatomic particles traveling in a straight line.
lipid: A biological molecule which is soluble in nonpolar solvents.
liquefaction: Changing a gas to a liquid. liquid: A state characterized by particles in such close proximity that their random motion appears to be a vibration about a moving point.
liquid crystal: A substance which has order in the arrangement of its particles in only one or two dimensions.
liter: A unit of volume equal to 1 dm3.
London forces: see dispersion forces
macromolecule: A crystal which consists of a single molecule with all component atoms bonded in a network fashion.
magnetohydrodynamics: The study of plasmas.
malleability: The property of a substance which allows it to be hammered into thin sheets.
manometer: A device for measuring gas pressure.
mass: The measure of the amount of matter.
mass defect: The difference between the mass of a nucleus and the sum of the masses of the particles from which it was formed.
mass number: The number of nucleons in an atom.
mass spectrometry: The separation of atoms or radicals on the basis of the varied effects of electric and magnetic fields on different masses.
matter: Anything which exhibits the property of inertia.
mean free path: The average distance a molecule travels between collisions.
melting point: The temperature at which the vapor pressures of the solid and liquid phases of a substance are equal.
meson: A subatomic particle classed as a hadron.
metal: An element which tends to lose electrons in chemical reactions.
metallic bond: A force holding metal atoms together and characterized by free electrons.
metalloid: An element which has properties characteristic of a metal and a nonmetal.
miscible: Two liquids which are mutually soluble in all proportions.
mixture: A combination of two or more substances.
mobile phase: The fluid containing the mixture to be analyzed in chromatography.
moderator: A substance used to slow neutrons in a nuclear reactor.
molal boiling point constant: A value characteristic of a solvent indicating the rise in the boiling point of 1 kilogram of the solvent if it contains 1 mole of particles.
molal freezing point constant: A value characteristic of a solvent indicating the drop in the freezing point of 1 kilogram of the solvent if it contains 1 mole of particles.
molality: A unit of concentration equal to the number of moles of solute in 1 kilogram of solvent.
molar heat capacity: The amount of heat required to change the temperature of 1 mole of a substance by 1 Celsius degree.
molar volume: The volume occupied by 1 mole of gas molecules at standard temperature and pressure and equal to 22.4 dm3.
molarity: A unit of concentration equal to the number of moles of solute in 1 dm3 of solution.
mole: Avogadro's number of objects = 6.02 x 1023.
mole fraction: A unit of concentration equal to the number of moles of solute in a mole of solution.
molecular formula: A formula indicating the actual number of each kind of atom contained in a molecule.
molecular mass: The mass of a molecule found by adding the atomic masses of the atoms comprising the molecule.
molecular orbital theory: A model of molecular structure based upon the formation of molecular orbitals from corresponding atomic orbitals.
molecule: A particle in which the constituent atoms are held together by covalent bonds.
momentum: The product of mass and velocity.
nematic substance: A liquid crystal with order in one dimension only.
net ionic equation: A chemical equation indicating only those substances taking part in the reaction and omitting spectator ions.
neutral: Neither acidic nor basic (electrolytes). Neither positive nor negative (electricity).
neutralization: The combining of an acid and a base until the amounts present correspond to the proportions shown by the equation for their reaction.
neutron: A neutral particle found in the nucleus of an atom and having a mass of approximately one atomic mass unit.
nitrile: A class of organic compounds characterized by the presence of the --CN group.
nitro: A class of organic compounds characterized by the presence of the --NO2 group.
noble gas: Any element from Group VIIIA of the periodic table.
nonmetal: An element which tends to gain electrons in chemical reactions.
nonvolatile: A substance which has a high boiling point, strong intermolecular forces, and a low vapor pressure at room temperature.
nuclear magnetic resonance spectroscopy: A spectroscopic method based on the energy required to reorient a nucleus with a magnetic field with respect to an external magnetic field.
nucleic acid: A biological polymer involved in genetic transfer and cell metabolism.
nucleon: A particle found in the nucleus of an atom. A proton or neutron.
nuclide: An element containing a specific number of protons and a specific number of neutrons.
octahedral: A molecular or ionic shape in which six particles are clustered about a central particle at the vertices of a regular octahedron.
octane rating: A system of rating gasoline based upon the proportions of heptane and 2,2,4-trimethylpentane in the mixture.
octet rule: The tendency of atoms to react in such a way that they acquire eight electrons in their outer level. He with 2 electrons also conforms.
ohm: The unit of electric resistance. One volt will force 1 ampere through 1 ohm.
olefln: Another name for an alkene.
optical isomers: Mirror image molecules which rotate a plane of polarized light in opposite directions.
optically active: A property of substances characterized by their ability to rotate a plane of polarized light.
orbital: The space which can be occupied by O, 1, or 2 electrons with the same energy level, energy sublevel, and special orientation.
orbital theory. The energy required to break a bond. In molecular orbital theory, a molecular orbital which is at a lower energy level than the atomic orbitals from which it was formed.
organic: Related to carbon compounds.
organic oxidation reaction: The combustion of an organic compound to produce carbon dioxide and water.
osmotic pressure: The pressure developed across a semipermeable membrane by differential diffusion through the membrane.
oxidation: The loss of electrons.
oxidation number: The charge on an atom if the electrons in a compound are assigned in an arbitrary manner according to established rules.
oxidizing agent: A substance which tends to gain electrons.
packing: An adsorbent used in columns for column and gas chromatography.
pair repulsion: A model for molecular shape based upon the assumption that electron clouds will repel each other and be as far away from each other as possible.
paper chromatography: A chromatographic method based upon the movement of a solvent through paper by capillary action.
parent chain: The longest continuous chain of carbon atoms used for naming organic molecules.
partially miscible: Two liquids which are soluble in each other to a limited extent.
pascal: The SI unit of pressure equal to 1 N/m2.
percentage composition: The proportion of an element present in a compound found by dividing the mass of the element present by the mass of the whole compound and multiplying by a hundred.
periodic law: The properties of the elements are a periodic function of their atomic numbers.
periodic table: A pictorial arrangement of the elements based upon their electron configurations.
petroleum: A natural mixture of organic compounds found in liquid form.
pH: The negative logarithm of the hydronium ion concentration.
phase: A physically distinct section of matter set off from the surrounding matter by physical boundaries.
phase diagram: A graphical representation of the vapor pressures of the solid and liquid forms of a substance.
photoelectric effect: The ejection of electrons from a surface which is exposed to light.
physical change: A change in which the substance or substances present after the change are the same chemically.
physical properties: The characteristics of a material as it is subjected to physical changes.
pi bond: A bond formed by the sideways overlap of p orbitals.
plasma: A high temperature physical state characterized by the separation of atoms into electrons and nuclei.
pOH: The negative logarithm of the hydroxide ion concentration.
polarimeter: A device for measuring the rotation of plane polarized light.
polarity: Unsymmetrical charge distribution.
polarized light: Light in which the field variations are all in the same plane.
polyatomic ion: A group of atoms bonded to each other covalently put possessing an overall charge. A very large molecule made from simple units
repeated many times.
polymerization: The reaction producing a polymer from monomers.
polymorphism: The property of existing in more than one crystalline form.
polyprotic acid: An acid with more than one ionizable hydrogen atom.
position isomers: Two molecules having the same formula but differing in the position to which a substituent is attached to the parent chain.
positron: A subatomic particle identical to an electron except possessing a positive charge. The antiparticle of the electron.
potential difference: The difference in potential energy of electrons located at different points.
potential energy: Energy of an object due to its position.
precipitate: A solid produced from a reaction occurring in aqueous solution.
precision: The possible error in a measurement
pressure: The force per unit area.
protein: A biological polymer of amino acids.
proton: A positive particle found in nuclei and having a mass of approximately 1 atomic mass unit.
quadridentate: A ligand which attaches to a central ion in four locations.
quantum number: A number describing a property of an electron in an atom.
quantum theory: The concept that energy is transferred in discrete units.
quark: A theoretical particle believed to be a constituent of a hadron.
radiant energy: Energy in transit between two objects.
radical: A fragment of a molecule. It is neutral yet at least one atom is lacking its octet of electrons.
radioactivity: The spontaneous disintegration of nuclei.
Raoult's law: The vapor pressure of a solution of a nonvolatile solute is the product of the vapor pressure of the pure solvent and the mole fractions of the solvent.
reaction mechanism: The actual step-by-step description of the interaction of atoms, ions, and molecules in a reaction.
reaction rate: The rate of disappearance of a reactant or the rate of appearance of a product.
redox reaction: A reaction involving the transfer of electrons.
reducing agent: A substance that tends to donate electrons.
reduction: The gain of electrons.
Refraction: The bending of a beam of light as it passes from one medium into another.
refractometer: A device for measuring the refraction of light.
resonance: The phenomenon in which several equally valid dot diagrams can be drawn for a substance. The actual substance is an average of all the possible arrangements.
reversible chemical change: Products can be changed back into the original reactants, under the proper conditions.
reversible thermodynamic change: An ideal change in which the difference in pressure causing the change is infinitesimal.
salt: A compound formed from the positive ion of a base and the negative ion of an acid.
saponification reaction: The reaction of an ester with a strong base to form a soap and glycerol.
saturated hydrocarbon: A hydrocarbon in which all carbon-carbon bonds are single bonds.
saturated solution: A solution in which undissolved solute is in equilibrium with dissolved solute.
scientific notation: Expression of numbers in the form M x 10n .
screw dislocation: A crystal defect in which the unit cells are improperly aligned.
semiconductor: A device in which the electrons are involved in bonding, but which may be made to conduct under the proper conditions.
shielding effect: The decrease in the force between outer electrons and the nucleus due to the presence of other electrons between them.
SI units: The internationally accepted set of standards for measurement.
side chain: A hydrocarbon radical attached to the parent chain of an organic molecule.
sigma bond: A bond formed by the end-to-end overlap of atomic orbitals.
significant digits: Digits in the value of a measurement indicating the quantity to a precision justified by the measuring device and technique used to make the measurement.
single displacement: A reaction in which one element replaces another in a compound.
smectic substance: A liquid crystal having order in two dimensions.
solid: A physical state characterized by particles in such close proximity that their random motion appears to be vibration about a fixed point.
solubility: The quantity of a solute which will dissolve in a specific quantity of solvent at a specific temperature.
solubility product constant: The equilibrium constant for the dissolving of a slightly soluble salt.
solute: The substance present in lesser quantity in a solution.
solution: A homogeneous mixture composed of solute and solvent.
solution equilibrium: Solute is dissolving and crystallizing at the same rate.
solvation: The attaching of solvent particles to solute particles.
solvent: The substance present in the greater amount in a solution.
space lattice: The theoretical arrangement pattern of the unit cells in a crystal.
specific heat capacity: The amount of heat required to raise the temperature of 1 gram of a substance by 1 Celsius degree.
specific rate constant: A constant used to determine the rate of a reaction from the concentration of the reactants.
spectator ion: An ion present in a solution but not taking part in the reaction.
spin: A property of subatomic particles which corresponds most closely with our concept of rotation about an axis.
spontaneous: Occurring without outside influence.
square planar: An arrangement of particles in a complex ion in which the ligands are arranged in a plane with the central ion and form a square with the central ion in the center.
stability: The tendency (or lack of it) for a compound to disintegrate or decompose.
standard solution: A solution whose concentration is known with precision.
standard state: A reference set of conditions for thermodynamic measurements equal to 25oC, 101.325 kPa, and 1M.
standard temperature and pressure: A set of reference conditions for dealing with gases equal to OoC and 101.325 kPa.
starch: A biological polymer of glucose.
state: A physical property of a phase designating it as solid, liquid, gas, or plasma.
state function: Thermodynamic quantity which is determined solely by the conditions, not the method of arriving at those conditions.
stationary phase: The adsorbent in chromatography.
stoichiometry: The solution of problems involving specific quantities of a substance or substances.
strong acid or base: A completely ionized electrolyte.
structural isomers: Two compounds with the same formula but differing arrangements of the parent carbon chain.
sublimation: The change directly from solid to gas.
substituent: A hydrocarbon branch or nonhydrocarbon group attached to the parent chain or ring in organic compounds.
substitution reaction: A reaction in organic compounds in which a hydrogen atom or substituent is replaced by another substituent.
supercooled liquid: A liquid cooled below its normal freezing point without having changed state to the solid form. A metastable state.
supersaturated solution: A solution containing more solute than a saturated solution at the same temperature. A metastable state.
surface tension: The apparent "skin" effect on the surface of a liquid due to unbalanced forces on the surface particles.
suspension: A dispersion of particles larger than 100 nm throughout a continuous medium.
symmetry: The property of being balanced with respect to the relative positions of atoms or substituents on opposite sides of an imaginary center or axis.
synchrotron: A device for accelerating subatomic particles in a circular path.
synthesis: Formation of a compound from two or more simpler substances.
synthetic element: An element not occurring in nature produced by means of nuclear reactions.
technology: The application of scientific principles for practical use.
temperature: A measure of the average kinetic energy of molecules.
ternary: A compound formed from three elements.
tetrahedral: An arrangement in which four particles surround a central particle at angles of 109.5o to each other.
thermodynamics: The study of the interaction of heat and matter.
thermometer: A device for measuring temperature.
thin layer chromatography: A chromatographic method utilizing an adsorbent spread over a flat surface in a thin layer.
time: The interval between two occurrences.
titration: A laboratory technique for measuring the relative strength of solutions.
tracer: A nuclide used to follow a reaction or process.
transistor: An electronic device whose operation is based upon the behavior of certain crystals with deliberate built-in defects.
transition element: An element whose highest energy electron is in a d sublevel.
transmutation: The change of one element into another.
transuranium element: An element with Z > 92.
tridentate: A ligand which attaches to the central ion in three locations.
triple bond: A covalent bond in which two atoms share three pairs of electrons.
triple point: The temperature and pressure at which all three phases of a substance are in equilibrium.
Tyndall effect: The scattering of light by colloids.
ultraviolet spectroscopy: A spectroscopic technique using light of wavelength slightly less than visible light and lending evidence to the electronic structure of atoms and molecules.
uncertainty principle: The impossibility of measuring exactly both the position and the momentum of an object at the same time.
unit cell: The simplest unit of repetition in a crystal lattice.
unsaturated molecule: An organic molecule containing at least one double or triple bond.
unsaturated solution: A solution containing less solute than a saturated solution at the same temperature.
van der Waals forces: Weak intermolecular forces of attraction between molecules.
van der Waals radii: The radius of an atom in the direction of adjacent nonbonded atoms.
vapor equilibrium: The state in which evaporation and condensation are taking place at the same rate.
vapor pressure: The pressure generated by a vapor in equilibrium with its liquid.
velocity: Speed expressed as a vector quantity.
viscosity: The resistance of a fluid to flow.
visible spectroscopy: A spectroscopic method useful in investigating the behavior of electrons in atoms.
volatile: A substance with a low boiling point, weak intermolecular forces, and a high vapor pressure at room temperature.
volt: The unit of electric potential difference.
voltaic cell: An electrochemical cell in which a chemical reaction generates an electric current.
wave: A periodic disturbance in a medium.
wave equation: A mathematical expression treating the electron as a wave and providing the amplitude of the wave at specific points in space with reference to the nucleus as the origin.
wavelength: The distance between corresponding crests or troughs in a wave.
wave-particle duality of nature: The property of particles behaving as waves as well as particles and the property of waves behaving as particles as well as waves.
weak (acids and bases): An electrolyte which is only slightly ionized.
weak forces: Attractive forces between molecules and consisting of dipole-dipole, dipole-induced dipole, and dispersion forces.
work: A force moving through a distance.
Ah Yaz Indeed!
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