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Octahedron A three-dimensional geometric figure having eight triangular sides
Octet Rule the observation that atoms of nonmetals tend to form the most stable molecules when they are surrounded by eight electrons (to fill their valence orbitals)
Odd Electron An unpaired electron, particularly in a molecule having an uneven number of valence electrons
Open hearth process a process for producing steel by oxidizing and removing the impurities in molten iron using external heat and a blast of air or oxygen
Open System A system that can exchange energy and matter with its surroundings
Optical isomerism isomerism in which the isomers have opposite effects on plane-polarized light
Orbital a specific wave function for an electron in an atom The square of this function gives the probability distribution for the electron
d-Orbital splitting a splitting of the d-orbitals of the metal ion in a complex such that the orbitals pointing at the ligands have higher energies than those pointing between the ligands
Order (of reactant) the positive or negative exponent, determined by experiment, of the reactant concentration in a rate law
Ore A mixture of minerals and rock from which a desired metal is obtained
Organic acid an acid with a carbon-atom backbone; often contains the carboxyl group
Organic chemistry the study of carbon-containing compounds (typically chains of carbon atoms) and their properties
Organic Compound A hydrogen-containing carbon compound, which may also contain oxygen nitrogen, sulfur, and/or other elements
Osmosis the flow of solvent into a solution through a semipermeable membrane
Osmotic Pressure The pressure developed by the flow of solvent through a semipermeable membrane during osmosis
Ostwald process a commercial process for producing nitric acid by the oxidation of ammonia
Outer Core The intermediate portion of the earth, composed of molten iron and smaller amounts of lighter elements
Overpotential The voltage in excess of the voltaic cell potential that is needed to cause electrolysis to occur
Oxidation an increase in oxidation state (a loss of electrons)
Oxidation-reduction (redox) reaction a reaction in which one or more electrons are transferred
Oxidation states a concept that provides a way to keep track of electrons in oxidation-reduction reactions according to certain rules
Oxidizing agent (electron acceptor) a reactant that accepts electrons from another reactant
Oxyacid an acid in which the acidic proton is attached to an oxygen atom
Ozone O3, the form of elemental oxygen in addition to the much more common O2-
Paramagnetism a type of induced magnetism, associated with unpaired electrons, that causes a substance to be attracted into the inducing magnetic field
Partial pressures The pressure that a gas in a mixture of gases would exert if it occupied the same container alone at the same temperature
Particle accelerator a device used to accelerate nuclear particles to very high speeds
Pascal the SI unit of pressure; equal to newtons per meter squared
Pauli exclusion principle in a given atom no two electrons can have the same set of four quantum numbers
Penetration effect the effect whereby a valence electron penetrates the core electrons, thus reducing the shielding effect and increasing the effective nuclear charge
Percent dissociation the ratio of the amount of a substance that is dissociated at equilibrium to the initial concentration of the substance in a solution, multiplied by 100
Percent yield the actual yield of a product as a percentage of the theoretical yield
Period In the periodic table, a horizontal row of elements whose properties change progressively with change of atomic number
Periodic Law The chemical and physical properties of the elements are periodic functions of their atomic numbers
Periodic table a chart showing all the elements arranged in columns with similar chemical properties
Petrochemicals chemicals obtained from petroleum either by steam cracking or as by-products of refinery operations They serve as raw materials for the chemical industry
pH The negative logarithm of the H + ion concentration in a solution
pH curve (titration curve) a plot showing the pH of a solution being analyzed as a function of the amount of titrant added
pH scal a log scale based on 10 and equal to -log[H+J; a convenient way to represent solution acidity
Phase diagram A diagram showing the temperature-pressure relations among the liquid, solid, and vapor states of a substance
Phenyl group the benzene molecule minus one hydrogen atom
Phospholipids esters of glycerol containing two fatty acids and a phosphate group Having nonpolar tails and polar heads, they tend to form bilayers in aqueous solution
Phosphorescence The continued emission of light by a substance after the exciting radiation has been discontinued
Photochemical Glass Glass that darkens reversibly on exposure to light because of the presence of photosensitive silver salts
Photochemical smog air pollution produced by the action of light on oxygen, nitrogen oxides, and unburned fuel from auto exhaust to form ozone and other pollutants
Photodissociation The dissociation of a molecule into its atoms that is induced by radiant energy
Photoelectric Effect The ejection of electrons from a metallic surface by radiant energy
Photoelectrolysis The use of light energy, converted into electrical energy by an n-type semiconductor, for the electrolysis of water
Photographic Developing Intensifying the image on a photographic film through reduction of the silver salts with a reducing agent
Photographic Negative The image in which light and dark regions are reversed on a photographic film
Photoionization The removal of an electron from a molecule, atom, or ion by radiant energy
Photon a quantum of electromagnetic radiation
Physical change a change in the form of a substance, but not in its chemical composition; chemical bonds are not broken in a physical change
Physical Property An intensive property of a substance, such as color, density, melting point, or boiling point, that can be observed without changing the chemical nature of the substance
Physical States of Matter The solid, liquid, olasma, and gaseous states that matter can assume
Pi bond a covalent bond in which parallel p orbitals share an electron pair occupying the space above and below the line joining the atoms
Planck's constant the constant relating the change in energy for a system to the frequency of the electromagnetic radiation absorbed or emitted; equal to 6.626 X 10-34 j/S
Plane-Polarized Light Radiant energy whose vibrations are in a single plane
pOH The negative logarithm of the OH - ion concentration in a solution
Polar Covalent Bond a covalent bond in which the electrons are not shared equally because one atom attracts them more strongly than the other
Polar molecule a molecule that has a permanent dipole moment
Polyatomic ion an ion containing a number of atoms
Polychromatic Referring to radiant energy composed of many wavelengths
Polyelectronic atom an atom with more than one electron
Polymer A molecule composed of many smaller molecules, or monomers
Polymerization a process in which many small molecules (monomers) are joined together to form a large molecule
Polypeptide a polymer formed from amino acids joined together by peptide linkages
Polyprotic acid an acid with more than one acidic proton It dissociates in a stepwise manner, one proton at a time
Porous disk a disk in a tube connecting two different solutions in a galvanic cell that allows ion flow without extensive mixing of the solutions
Porphyrin a planar ligand with a central ring structure and various substituent groups at the edges of the ring
Positional probability a type of probability that depends on the number of arrangements in space that yield a particular state
Positron A particle emitted from some radioactive nuclei that is positively charged but otherwise identical with the electron
Positron production a mode of nuclear decay in which a particle is formed having the same mass as an electron but opposite charge The net effect is to change a proton to a neutron
Potential energy energy due to position or composition
Potentiometer A device for the measurement of electric potential when no current is flowing through a circuit
Precipitation reaction a reaction in which an insoluble substance forms and separates from the solution
Precision the degree of agreement among several measurements of the same quantity; the reproducibility of a measurement
Preliminary Treatment of Ores Steps taken to concentrate the mineral in the ore and prepare it for reduction to the metal
Primary Cell a voltaic cell that is not rechargeable because the reactants are consumed irreversibly
Primary structure (of a protein) the order (sequence) of amino acids in the protein chain
Principal Quantum Number The quantum number that specifies the main energy level occupied by an electron in an atom
Probability distribution the square of the wave function indicating the probability of finding an electron at a particular point in space
Probability Function The square of the wave function for an electron, which is proportional to the probability of finding a particle at any given point; for an electron, the probable electron density
Product a substance resulting from a chemical reaction It is shown to the right of the arrow in a chemical equation
Promoters Impurities in a heterogeneous catalyst that increase catalytic activity
Propagation Step A step in a chain reaction mechanism that carries the reaction along
Protein a natural high-molecular-weight polymer formed by condensation reactions between amino acids
Proton a positively charged particle in an atomic nucleus
Pseudo-First-Order Reaction A second-order reaction carried out with a large excess of one reactant, with the consequence that the rate depends only on the concentration of the other reactant
Pseudo-Noble-Gas Configuration An electron configuration in which a principal energy level is filled through the d sublevel
Pure substance a substance with constant composition
Pyrometallurgy recovery of a metal from its ore by treatment at high temperatures

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