- A favourable interaction of two electrons with opposite m , values in the
- Pairing Energy
- Energy required to pair two electrons in the same orbital.
- Attraction toward a magnetic field, stronger than diamagnetism, but still
weak compared to ferromagnetism.
- Partial Pressure
- The pressure exerted by one gas in a mixture of gases.
- Particulate Matter
- Fine divided solid particles suspended in polluted air.
- Pauli Exclusion Principle
- No two electrons in the same atom may have identical sets of four quantum
- Percentage Ionization
- The percentage of the weak electrolyte that ionizes in a solution of given
- Percent by Mass
- 100% times the actual yield divided by theoretical yield.
- Percent Composition
- The mass percent of each element in a compound.
- Percent Purity
- The percent of a specified compound or element in an impure sample.
- The elements in a horizontal row of the periodic
- Regular periodic variations of properties of elements with atomic number
(and position in the periodic table).
- Periodic Law
- The properties of the elements are periodic functions of their atomic
- Periodic Table
- An arrangement of elements in order of increasing atomic numbers that also
- A compound containing oxygen in the -1 oxidation state. Metal peroxides
contain the peroxide ion, O22-
- Negative logarithm of the concentration (mol/L) of the H3O+[H+]
ion; scale is commonly used over a range 0 to 14.
- Phase Diagram
- Diagram that shows equilibrium temperature-pressure relationships for
different phases of a substance.
- Hydrocarbon derivative containing an [OH] group bound to an aromatic raing.
- Photochemical Oxidants
- Photochemically produced oxidizing agents capable of causing damage to
plants and animals.
- Photochemical Smog
- A brownish smog occurring in urban areas receiving large amounts of
sunlight; caused by photochemical (light-induced) reactions among nitrogen
oxides, hydrocarbons and other components of polluted air that produce
- Photoelectric Effect
- Emission of an electron from the surface of a metal caused by impinging
electromagnetic radiation of certain minimum energy; current increases with
increasing intensity of radiation.
- A packet of light or electromagnetic radiation; also called quantum of
- Physical Change
- A change in which a substance changes from one physical state to another
but no substances with different composition are formed. Example Gas to Liquid
- A physical state of matter which exists at extremely high temperatures in
which all molecules are dissociated and most atoms are ionized.
- Polar Bond
- Covalent bond in which there is an unsymmetrical distribution of electron
- A device used to measure optical activity.
- The buildup of a product of oxidation or a reduction of an electrode,
preventing further reaction.
- Refers to ligands with more than one donor atom.
- A compound that contains more than one double bond per molecule.
- The combination of many small molecules to form large molecules.
- A large molecule consisting of chains or rings of linked monomer units,
usually characterized by high melting and boiling points.
- Refers to substances that crystallize in more than one crystalline
- Polyprotic Acid
- An Acid that can form two or more hydronium ions per molecule; often a
least one step of ionization is weak.
- A Nuclear particle with the mass of an electron but opposite charge.
- Potential Energy
- Energy that matter possesses by virtue of its position, condition or
- An insoluble solid formed by mixing in solution the constituent ions of a
slightly soluble solution.
- Primary Standard
- A substance of a known high degree of purity that undergoes one invariable
reaction with the other reactant of interest.
- Primary Voltaic Cells
- Voltaic cells that cannot be recharged; no further chemical reaction is
possible once the reactants are consumed.
- A subatomic particle having a mass of 1.0073 amu and a charge of +1, found
in thew nuclei of atoms.
- PseudobinaryIonic Compounds
- Compounds that contain more than two elements but are named like binary