| Absolute zero |
the lowest possible temperature, -273.15oC (0
Kelvin); at this temperature, molecules are at their lowest energy state |
| Absorbance |
the extent to which radiant energy is absorbed by a substance |
| Absorption spectra |
spectra resulting from the adsorption of radiant energy by
molecules and ions |
| Accuracy |
the correctness of the value obtained in a measurement |
| Acidic anhydride |
a nonmetal oxide that can combine with water to form an acid |
| Acid |
a substance that produces hydrogen ions in solution; a proton
donor |
| Acid-base indicators |
a substance that marks the endpoint of an acid-base titration
by changing color |
| Acid dissociation constant (Ka) |
the equilibrium constant for a reaction in which a proton is
removed from an acid by H2O to form the conjugate base and H3O+ |
| Acidic oxide |
a covalent oxide that dissolves in water to give an acidic
solution |
| Actinides |
the 14 inner transition metals beginning with actinium |
| Activated complex (transition states) |
the arrangement of atons found at the top of potential energy
barrier as a reaction proceeds from reactants to products |
| Activation energy |
the threshold energy that much be overcome to produce a
chemical reaction |
| Active site |
a location on the surface of a heterogeneous catalyst to
which reactants bind and at which they pass through the transition state |
| Addition Polymerization |
a tye of polymerization in which the monomers simply add
together to form the polymer, with no other products |
| Addition reaction |
a reaction in which one molecule adds to another without the
loss of atoms from either |
| Adsorbent |
a substance having a large surface area to which other
surfaces adhere |
| Adsorption |
the collection of one substance on the surface of another |
| Alcohol |
A compounding containing the hydroxy (O-H) group attached to
a hydrocarbon |
| Aldehyde |
an organic compound containing the carbonyl group bonded to
at least one hydrogen atom |
| Aliphatic hydrocarbon |
hydrocarbons of the alkane, alkene, or alkyne groups |
| Alkali metal |
a Group 1A metal |
| Alkaline earth metal |
a Group 2A metal |
| Alkane |
hydrocarbons containing only sigma bonds (single bonds); has
a general formula for CnH2n+2 |
| Alkene |
hydrocarbons containing a pi bond (double); general formula
is CnH2n |
| Alkyne |
hydrocarbons containing two bonds between adjacent carbon
atoms (a triple bond); general formula of CnH2n-2 |
| Allotropism |
the existence of a substance in more than one form, usually
the same state |
| Alloy |
a substance that contains a mixture of elements and has
metallic properties |
| Alpha particle (a) |
a radioactive emission identical with the helium nucleus; He2+ |
| Amalgam |
An alloy of mercury with one or more other metals |
| Amide |
A compound containg the -CON- (C double bonded to O) attached
to hydrogen or hydrocarbon residues |
| Amine |
an organic base derived from ammonia in which one or more of
the hydrogen atons are replaced by organic groups |
| a-Amino acid |
an organic acid in which an aminoi group and an R gruop are
attached to the carbon atom next to the carboxyl group |
| Amorphous solid |
a supercooled liquid with teh external appearance of a solid
but not having a crystalline structure |
| Ampere |
the unit of measurement of electric current, equal to one
coulomb per second |
| Amphoteric |
having the ability to react either as an acid or a base |
| Anion |
a negatively charged ion, which is accordingly attracted to
the anode |
| Anode |
the electrode in a galvanic cell at which oxidation occurs |
| Antibonding molecular orbital |
an orbital higher in energy than the atomic orbitals of which
it is composed |
| Antineutrino |
a very small neutral particle emitted along with an electron |
| Aqueous solution |
a solution in which water is the dissolving medium or solvent |
| Aromatic hydrocarbon |
one of a s special class of cyclic unsaturated hydrocarbons,
the simplest of which is benzene |
| Arrhenius acid |
a substance that dissociates in aqueous solution to produce
hydrogen ions |
| Arrhenius base |
a substance that dissociates in aqueous solution to produce
hydroxide ions |
| Arrhenius equation |
the equation expressing the relationship between the kinetic
rate constant and temperature |
| Atactic chain |
a polymer chain in which the substituent groups such as CH3
are randomly distributed along the chain |
| Atmosphere |
a pressure unit corresponding tothe pressure exerted by the
earth's atmosphere at sea level at 0oC, equal to the pressure of a column of
mercury 76.0 in height |
| Atom |
the smallest part of an element |
| Atomic mass |
the average mass of the atoms of an element relative to an
atom selected as the standard |
| Atomic mass unit |
the unit of atomic masses equal to 1/12 the mass of the
carbon isotope having a mass of 12 such units |
| Atomic number |
the charge on the nucleus of an atom |
| Atomic radius |
half the idistance between the nuclei in a molecule
consisting of identical atoms |
| Atomic solid |
a solid that contains atoms at the lattice points |
| Atomic weight |
the weighted average mass of atoms in a naturally occuring
element |
| Aufbau principle |
the principle stating that as protons are added one by one to
the nucleus to build up the elements electrons are similarly added to hydrogenlike
orbitals |
| Autoionization |
the transfer of a proton from one molecule to another of the
same substance |
| Average bond energy |
the average energy per mole required to dissociate bonds of a
particular order between two atoms |
| Avogadro's law |
equal volumes of gases at teh same temperature and pressure
contain the same number of particles |
| Avogadro's number |
the number of atoms in exactly 12 grams of puer C-12, equal
to 6.022 x 1023 |
| Axial bonds |
bonds parallel to the axis that is perpendicular to the plane
containing the equator of a molecule |
| Azeotrope |
a solution of liquids that has a constant boiling point
because the composition of the vapor is the same as the composition of the liquid |
| Azimuthal quantum number |
(l) the quantum number relating to the shape of an
atomic orbital, which can assume any integral value from 0 to n-1 for each
value of n |
