| 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 |
