GLOSSARY
Acid - substance that produces H3O+ when dissolved in
water
Acid salt contains an anion that can act as an acid (proton donor); examples
are NaHSO4 and NaH2SO4
Acid-base reaction - reaction involving the transfer of a hydrogen ion between reactant
species
Activation energy (Ea) - energy necessary in order for a reaction to take
place
Activity is the effective concentration of a species. It is obtained as the
product of an activity coefficient and the ratio of the stoichiometic
concentration or pressure to that of a reference state.
Alkali metal - element in group 1
Alkaline earth metal - element in group 2
Alpha ( ) particle
is a combination of two protons and two
neutrons identical to the helium ion, that is, 4He2+.
Alpha particles are emitted in some radioactive decay
processes.
Alpha particle (α particle) - positively charged particle consisting of two protons and two
neutrons
Amphoteric - species that can act as either an acid or a
base
Anion - negatively charged atom or molecule (contains more electrons than
protons)
Anode - electrode in an electrochemical cell at which oxidation occurs;
information about the anode is recorded on the left side of the salt bridge in
cell notation
Aqueous solution - solution for which water is the solvent
Arrhenius equation - mathematical relationship between the rate constant and the
activation energy of a reaction
Atom - smallest particle of an element that can enter into a chemical
combination.
Atomic mass - average mass of atoms of an element, expressed in
amu
Atomic number (Z) - number of protons in the nucleus of an atom
Atomic orbital - mathematical function that describes the behavior of an electron in
an atom (also called the wavefunction), it can be used to find the probability
of locating an electron in a specific region around the nucleus, as well as
other dynamical variables
Avogadro’s law - volume of a gas at constant temperature and pressure is proportional
to the number of gas molecules
Avogadro’s number (NA) - experimentally determined value of the number of entities comprising
1 mole of substance, equal to 6.022 × 1023 mol−1
balanced equation - chemical equation with equal numbers of atoms for each element in the
reactant and product
Base - substance that produces OH− when dissolved in
water
binary acid - compound that contains hydrogen and one other element, bonded in a
way that imparts acidic properties to the compound (ability to release H+ ions
when dissolved in water)
binary compound - compound containing two different elements.
boiling point - temperature at which the vapor pressure of a liquid equals the
pressure of the gas above it
bond energy - (also, bond dissociation energy) energy required to break a covalent
bond in a gaseous substance
bond length - distance between the nuclei of two bonded atoms at which the lowest
potential energy is achieved
Boyle’s law - volume of a given number of moles of gas held at constant temperature
is inversely proportional to the pressure under which it is
measured
Calorie (cal) - unit of heat or other energy; the amount of energy required to raise
1 gram of water by 1 degree Celsius; 1 cal is defined as 4.184
J
Calorimeter - device used to measure the amount of heat absorbed or released in a
chemical or physical process
Calorimetry - process of measuring the amount of heat involved in a chemical or
physical process
Catalyst - substance that increases the rate of a reaction without itself being
consumed by the reaction
Cathode - electrode in an electrochemical cell at which reduction occurs;
information about the cathode is recorded on the right side of the salt bridge
in cell notation
Cation - positively charged atom or molecule (contains fewer electrons than
protons)
Celsius (0C) - unit of temperature; water freezes at 0 °C and boils at 100 °C on
this scale.
Charles’s law - volume of a given number of moles of gas is directly proportional to
its kelvin temperature when the pressure is held constant
Chemical change - change producing a different kind of matter from the original kind
of matter.
Chemical energy is the energy associated with chemical bonds and intermolecular
forces.
Chemical equation - symbolic representation of a chemical reaction
Chemical property - behavior that is related to the change of one kind of matter into
another kind of matter.
Chemical symbol - one-, two-, or three-letter abbreviation used to represent an element
or its atoms
Chemical thermodynamics - area of science that deals with the relationships between heat, work,
and all forms of energy associated with chemical and physical
processes
Chemistry - study of the composition, properties, and interactions of
matter.
Clausius-Clapeyron equation - mathematical relationship between the temperature, vapor pressure,
and enthalpy of vaporization for a substance
Coefficient - number placed in front of symbols or formulas in a chemical equation
to indicate their relative amount
Collision theory - model that emphasizes the energy and orientation of molecular
collisions to explain and predict reaction kinetics
Combustion reaction vigorous redox reaction producing significant amounts of energy in
the form of heat and, sometimes, light
Complete ionic equation - chemical equation in which all dissolved ionic reactants and
products, including spectator ions, are explicitly represented by formulas for
their dissociated ions
Complex ion - ion consisting of a transition metal central atom and surrounding
molecules or ions called ligands
Compounds - pure substance that can be decomposed into two or more
elements.
Concentrated - qualitative term for a solution containing solute at a relatively
high concentration
Concentration - quantitative measure of the relative amounts of solute and solvent
present in a solution
Condensation - change from a gaseous to a liquid state
Coordination number is the number of positions around a central atom where ligands can be
attached in the formation of a complex. Applied to a crystalline solid,
coordination number signifies the number of nearest neighboring atoms (or ions
of opposite charge) to any given atom (or ion) in a
crystal.
Coordination number number of atoms closest to any given atom in a crystal or to the
central metal atom in a complex
Covalent bond - attractive force between the nuclei of a molecule’s atoms and pairs
of electrons between the atoms
Covalent bond - bond formed when electrons are shared between atoms
Covalent compound - (also, molecular compound) composed of molecules formed by atoms of
two or more different elements
Covalent radius - one-half the distance between the nuclei of two identical atoms when
they are joined by a covalent bond
Cubic centimeter (cm3) - volume of a cube with an edge length of exactly 1
cm.
Cubic meter (m3) - SI unit of volume.
d orbital - region of space with high electron density that is either four lobed
or contains a dumbbell and torus shape; describes orbitals with l = 2. An electron in this orbital is called a d electron
Dalton (Da) - alternative unit equivalent to the atomic mass
unit
Dalton’s atomic theory - set of postulates that established the fundamental properties of
atoms
Density - ratio of mass to volume for a substance or
object.
Dilute - qualitative term for a solution containing solute at a relatively low
concentration
Dilution - process of adding solvent to a solution in order to lower the
concentration of solutes
Dipole moment - property of a molecule that describes the separation of charge
determined by the sum of the individual bond moments based on the molecular
structure
Dissociation - physical process accompanying the dissolution of an ionic compound in
which the compound’s constituent ions are solvated and dispersed throughout the
solution
Dissociation constant - equilibrium constant for the decomposition of a complex ion into its
components in solution
Dissolved - describes the process by which solute components are dispersed in a
solvent
Double bond - covalent bond in which two pairs of electrons are shared between two
atoms
E1 reaction is an elimination reaction in which the rate-determining step is
unimolecular.
E2 reaction is an elimination reaction in which the rate-determining step is
bimolecular.
Electrochemical cell is a device in which the electrons transferred in an oxidation
reduction reaction are made to pass through an electrical circuit. (See also
electrolytic cell and voltaic cell.)
Electrolysis - process using electrical energy to cause a nonspontaneous process to
occur
Electrolyte - substance that produces ions when dissolved in
water
Electrolytic cell - electrochemical cell in which electrolysis is used; electrochemical
cell with negative cell potentials
Electromagnetic radiation - energy transmitted by waves that have an electric-field component and
a magnetic-field component
Electromagnetic spectrum - range of energies that electromagnetic radiation can comprise,
including radio, microwaves, infrared, visible, ultraviolet, X-rays, and gamma
rays; since electromagnetic radiation energy is proportional to the frequency
and inversely proportional to the wavelength, the spectrum can also be specified
by ranges of frequencies or wavelengths
Electron - negatively charged, subatomic particle of relatively low mass located
outside the nucleus
Electron configuration - electronic structure of an atom in its ground state given as a
listing of the orbitals occupied by the electrons
Electron density - a measure of the probability of locating an electron in a particular
region of space, it is equal to the squared absolute value of the wave function
ψ
Electronegativity - tendency of an atom to attract electrons in a bond to
itself
Element - substance that is composed of a single type of atom; a substance
that cannot be decomposed by a chemical change.
Elementary reaction - reaction that takes place precisely as depicted in its chemical
equation
Endothermic process - chemical reaction or physical change that absorbs heat
Energy - capacity to supply heat or do work
Enthalpy (H) - sum of a system’s internal energy and the mathematical product of its
pressure and volume
Enthalpy change (ΔH) - heat released or absorbed by a system under constant pressure during
a chemical or physical process
Entropy (S) - state function that is a measure of the matter and/or energy
dispersal within a system, determined by the number of system microstates often
described as a measure of the disorder of the system
Equilibrium - in chemical reactions, the state in which the conversion of reactants
into products and the conversion of products back into reactants occur
simultaneously at the same rate; state of balance
Equilibrium constant (K) - value of the reaction quotient for a system at
equilibrium
Exothermic process - chemical reaction or physical change that releases
heat
f orbital - multilobed region of space with high electron density, describes
orbitals with l = 3. An electron in this orbital is called an f electron
Faraday’s constant (F) - charge on 1 mol of electrons; F = 96,485 C/mol e−
First law of thermodynamics
- internal energy of a system changes due to heat flow in or out of the
system or work done on or by the system
Formula mass - sum of the average masses for all atoms represented in a chemical
formula; for covalent compounds, this is also the molecular
mass
Frequency (ν) - number of wave cycles (peaks or troughs) that pass a specified point
in space per unit time
Frequency factor (A) - proportionality constant in the Arrhenius equation, related to the
relative number of collisions having an orientation capable of leading to
product formation
Galvanic cell - electrochemical cell that involves a spontaneous oxidation-reduction
reaction; electrochemical cells with positive cell potentials; also called a
voltaic cell
Gas - state in which matter has neither definite volume nor
shape.
Gibbs free energy change (G) - thermodynamic property defined in terms of system enthalpy and
entropy; all spontaneous processes involve a decrease in G
Group - vertical column of the periodic table
Half-life of a reaction (tl/2) - time required for half of a given amount of reactant to be
consumed
Half-reaction - an equation that shows whether each reactant loses or gains electrons
in a reaction.
Halogen - element in group 17
Heat (q) - transfer of thermal energy between two bodies
Heat capacity (C) - extensive property of a body of matter that represents the quantity
of heat required to increase its temperature by 1 degree Celsius (or 1
kelvin)
Hertz (Hz) - the unit of frequency, which is the number of cycles per second,
s−1
Hess’s law - if a process can be represented as the sum of several steps, the
enthalpy change of the process equals the sum of the enthalpy changes of the
steps
Heterogeneous catalyst - catalyst present in a different phase from the reactants, furnishing
a surface at which a reaction can occur
Heterogeneous equilibria - equilibria between reactants and products in different
phases
Heterogeneous mixture - combination of substances with a composition that varies from point
to point.
Homogeneous catalyst - catalyst present in the same phase as the
reactants
Homogeneous equilibria - equilibria within a single phase
Homogeneous mixture (also, solution) combination of substances with a composition that
is uniform throughout.
Hund’s rule - every orbital in a subshell is singly occupied with one electron
before any one orbital is doubly occupied, and all electrons in singly occupied
orbitals have the same spin
Hydrogen bonding - occurs when exceptionally strong dipoles attract; bonding that exists
when hydrogen is bonded to one of the three most electronegative elements: F, O,
or N
Hypothesis - tentative explanation of observations that acts as a guide for
gathering and checking information.
Ideal gas - hypothetical gas whose physical properties are perfectly described by
the gas laws
ideal gas constant (R) - constant derived from the ideal gas equation R = 0.08226 L atm mol–1 K–1 or 8.314 L kPa
mol–1 K–1
Ideal gas law - relation between the pressure, volume, amount, and temperature of a
gas under conditions derived by combination of the simple gas
laws
Indicator - substance added to the sample in a titration analysis to permit
visual detection of the end point
Inert gas - (also, noble gas) element in group 18
Inner transition metal - (also, lanthanide or actinide) element in the bottom two rows; if in
the first row, also called lanthanide, of if in the second row, also called
actinide
Insoluble - of relatively low solubility; dissolving only to a slight
extent
Intensity - property of wave-propagated energy related to the amplitude of the
wave, such as brightness of light or loudness of sound
Internal energy (U) - total of all possible kinds of energy present in a substance or
substances
Ion - electrically charged atom or molecule (contains unequal numbers of
protons and electrons)
Ionic bond - electrostatic forces of attraction between the oppositely charged
ions of an ionic compound
Ionic bond strong electrostatic force of attraction between cations and anions
in an ionic compound
Ionic compound - compound composed of cations and anions combined in ratios, yielding
an electrically neutral substance
Ionization energy - energy required to remove an electron from a gaseous atom or ion. The
associated number (e.g., second ionization energy) corresponds to the charge of
the ion produced (X2+)
Isomers - compounds with the same chemical formula but different
structures
Isotopes - atoms that contain the same number of protons but different numbers
of neutrons
Joule (J) - SI unit of energy; 1 joule is the kinetic energy of an object with a
mass of 2 kilograms moving with a velocity of 1 meter per second, 1 J = 1 kg
m2/s and 4.184 J = 1 cal
Kc - equilibrium constant for reactions based on concentrations of
reactants and products
Kelvin (K)- SI unit of temperature; 273.15 K = 0
0C.
Kilogram (kg)- standard SI unit of mass; 1 kg = approximately 2.2
pounds.
Kinetic energy - energy of a moving body, in joules, equal to 1/2mv2 (where m = mass and v = velocity)
KP - equilibrium constant for gas-phase reactions based on partial
pressures of reactants and products
Lanthanide - inner transition metal in the top of the bottom two rows of the
periodic table
lattice energy (ΔHlattice) - energy required to separate one mole of an ionic solid into its
component gaseous ions
Law - statement that summarizes a vast number of experimental
observations, and describes or predicts some aspect of the natural
world.
law of conservation of matter - when matter converts from one type to another or changes form, there
is no detectable change in the total amount of matter
present.
Law of constant composition - (also, law of definite proportions) all samples of a pure compound
contain the same elements in the same proportions by mass
Law of definite proportions - (also, law of constant composition) all samples of a pure compound
contain the same elements in the same proportions by mass
Law of mass action - when a reversible reaction has attained equilibrium at a given
temperature, the reaction quotient remains constant
law of multiple proportions - when two elements react to form more than one compound, a fixed mass
of one element will react with masses of the other element in a ratio of small
whole numbers
Le Chatelier's principle - when a chemical system at equilibrium is disturbed, it returns to
equilibrium by counteracting the disturbance
Length - measure of one dimension of an object.
Lewis acid - any species that can accept a pair of electrons and form a coordinate
covalent bond
Lewis acid-base adduct - compound or ion that contains a coordinate covalent bond between a
Lewis acid and a Lewis base
Lewis base - any species that can donate a pair of electrons and form a coordinate
covalent bond
Lewis structure - diagram showing lone pairs and bonding pairs of electrons in a
molecule or an ion
Lewis symbol - symbol for an element or monatomic ion that uses a dot to represent
each valence electron in the element or ion
Ligand - molecule or ion that surrounds a transition metal and forms a complex
ion; ligands act as Lewis bases
Limiting reactant - reactant present in an amount lower than required by the reaction
stoichiometry, thus limiting the amount of product
generated
Linear - shape in which two outside groups are placed on opposite sides of a
central atom
Liquid - state of matter that has a definite volume but indefinite
shape
Liter (L) - (also, cubic decimeter) unit of volume; 1 L = 1,000
cm3.
Magnetic quantum number (ml) - quantum number signifying the orientation of an atomic orbital around
the nucleus; orbitals having different values of ml but the same subshell value of l have the same energy (are degenerate), but this degeneracy can be
removed by application of an external magnetic field
Main-group element - (also, representative element) element in columns 1, 2, and
12–18
Mass - fundamental property indicating amount of
matter.
Mass number (A) - sum of the numbers of neutrons and protons in the nucleus of an
atom
Mass percentage - ratio of solute-to-solution mass expressed as a
percentage
Mass-volume percent - ratio of solute mass to solution volume, expressed as a
percentage
Matter - anything that occupies space and has mass.
Metal - element that is shiny, malleable, good conductor of heat and
electricity
Metalloid - element that conducts heat and electricity moderately well, and
possesses some properties of metals and some properties of
nonmetals
Meter (m) - standard metric and SI unit of length; 1 m = approximately 1.094
yards
Milliliter (mL) - 1/1,000 of a liter; equal to 1 cm3
Mixture - matter that can be separated into its components by physical
means
Molality (m) - a concentration unit defined as the ratio of the numbers of moles of
solute to the mass of the solvent in kilograms
Molar mass - mass in grams of 1 mole of a substance
Molar solubility - solubility of a compound expressed in units of moles per liter
(mol/L)
Molarity (M) - unit of concentration, defined as the number of moles of solute
dissolved in 1 liter of solution
Mole amount of substance containing the same number of atoms, molecules,
ions, or other entities as the number of atoms in exactly 12 grams of
12C
Molecular compound - (also, covalent compound) composed of molecules formed by atoms of
two or more different elements
Molecular equation - chemical equation in which all reactants and products are represented
as neutral substances
Molecular formula - formula indicating the composition of a molecule of a compound and
giving the actual number of atoms of each element in a molecule of the
compound.
Molecular structure - arrangement of atoms in a molecule or ion
Molecule - bonded collection of two or more atoms of the same or different
elements
Monatomic ion - ion composed of a single atom
Nernst equation - equation that relates the logarithm of the reaction quotient
(Q) to nonstandard cell potentials; can be used to relate equilibrium
constants to standard cell potentials
Net ionic equation - chemical equation in which only those dissolved ionic reactants and
products that undergo a chemical or physical change are represented (excludes
spectator ions)
Neutralization reaction - reaction between an acid and a base to produce salt and
water
Neutron - uncharged, subatomic particle located in the nucleus
Noble gas - (also, inert gas) element in group 18
Nomenclature - system of rules for naming objects of interest
Nonelectrolyte - substance that does not produce ions when dissolved in
water
Nonmetal - element that appears dull, poor conductor of heat and
electricity
Nucleus - massive, positively charged center of an atom made up of protons and
neutrons
Nutritional calorie (Calorie) - unit used for quantifying energy provided by digestion of foods,
defined as 1000 cal or 1 kcal
Octet rule - guideline that states main group atoms will form structures in which
eight valence electrons interact with each nucleus, counting bonding electrons
as interacting with both atoms connected by the bond
Oxidation - process in which an element’s oxidation number is increased by loss
of electrons
Oxidation number - (also, oxidation state) the charge each atom of an element would have
in a compound if the compound were ionic
Oxidation-reduction reaction - (also, redox reaction) reaction involving a change in oxidation
number for one or more reactant elements
Oxidizing agent (also, oxidant) substance that brings about the oxidation of another
substance, and in the process becomes reduced
p orbital - dumbbell-shaped region of space with high electron density, describes
orbitals with l = 1. An electron in this orbital is called a p electron
Parts per billion (ppb) - ratio of solute-to-solution mass multiplied by 109
Parts per million (ppm) - ratio of solute-to-solution mass multiplied by 106
Pauli exclusion principle - specifies that no two electrons in an atom can have the same value
for all four quantum numbers
Percent composition - percentage by mass of the various elements in a
compound
Percent yield - measure of the efficiency of a reaction, expressed as a percentage of
the theoretical yield
Period - (also, series) horizontal row of the period table
Periodic law - properties of the elements are periodic function of their atomic
numbers.
Periodic table - table of the elements that places elements with similar chemical
properties close together
pH - logarithmic measure of the concentration of hydronium ions in a
solution
Photon - smallest possible packet of electromagnetic radiation, a particle of
light
Physical property - characteristic of matter that is not associated with any change in
its chemical composition
Pi bond (π bond) - covalent bond formed by side-by-side overlap of atomic orbitals; the
electron density is found on opposite sides of the internuclear
axis
Pnictogen - element in group 15
pOH - logarithmic measure of the concentration of hydroxide ions in a
solution
Polar covalent bond - covalent bond between atoms of different electronegativities; a
covalent bond with a positive end and a negative end
Polyatomic ion - ion composed of more than one atom
Precipitate - insoluble product that forms from reaction of soluble
reactants
Precipitation reaction - reaction that produces one or more insoluble products; when reactants
are ionic compounds, sometimes called double-displacement or
metathesis
Pressure - force exerted per unit area
Primary structure refers to the sequence of amino acids in the polypeptide chains that
make up a protein.
Principal quantum number (n) - quantum number specifying the shell an electron occupies in an
atom
Product - substance formed by a chemical or physical change; shown on the right
side of the arrow in a chemical equation
Properties are qualities or attributes that can be used to distinguish one
sample of matter from others.
Proton positively charged, subatomic particle located in the
nucleus
Pure substance - homogeneous substance that has a constant
composition
Quantum number - integer number having only specific allowed values and used to
characterize the arrangement of electrons in an atom
Rate constant (k) - proportionality constant in the relationship between reaction rate
and concentrations of reactants
Rate of reaction - measure of the speed at which a chemical reaction takes
place
Reactant - substance undergoing a chemical or physical change; shown on the left
side of the arrow in a chemical equation
Reducing agent (also, reductant) substance that brings about the reduction of
another substance, and in the process becomes oxidized
Reduction - process in which an element’s oxidation number is decreased by gain
of electrons
Resonance - situation in which one Lewis structure is insufficient to describe
the bonding in a molecule and the average of multiple structures is
observed
Resonance occurs when two or more plausible Lewis structures can be written for
a species. The true structure is a composite or hybrid of these different
contributing structures.
Reversible process - process that takes place so slowly as to be capable of reversing
direction in response to an infinitesimally small change in conditions;
hypothetical construct that can only be approximated by real processes
removed
s orbital - spherical region of space with high electron density, describes
orbitals with l = 0. An electron in this orbital is called an s electron
Salt - ionic compound that can be formed by the reaction of an acid with a
base that contains a cation and an anion other than hydroxide or
oxide
Second law of thermodynamics - entropy of the universe increases for a spontaneous
process
Series - (also, period) horizontal row of the period table
SI units (International System of Units) - standards fixed by international agreement in the International
System of Units (Le Systeme International d’Unites)
Sigma bond (σ bond) - covalent bond formed by overlap of atomic orbitals along the
internuclear axis
Single bond - bond in which a single pair of electrons is shared between two
atoms
Solid - state of matter that is rigid, has a definite shape, and has a fairly
constant volume
Solubility - the extent to which a substance may be dissolved in water, or any
solvent
Solubility product (Ksp) - equilibrium constant for the dissolution of a slightly soluble
electrolyte
Soluble - of relatively high solubility; dissolving to a relatively large
extent
Solute - solution component present in a concentration less than that of the
solvent
Solvent - solution component present in a concentration that is higher relative
to other components
sp hybrid orbital - one of a set of two orbitals with a linear arrangement that results
from combining one s and one p orbital
s-p mixing - change that causes σp orbitals to be less stable than πp orbitals due to the mixing of s and p-based molecular orbitals of similar energies.
sp2 hybrid orbital - one of a set of three orbitals with a trigonal planar arrangement
that results from combining one s and two p orbitals
sp3 hybrid orbital - one of a set of four orbitals with a tetrahedral arrangement that
results from combining one s and three p orbitals
Spin quantum number (ms) - number specifying the electron spin direction, either +1/2 or −1/2
Standard conditions of temperature and pressure (STP) -
273.15 K (0 °C) and 1 atm (101.325 kPa)
Standard entropy (S°) - entropy for a substance at 1 bar pressure; tabulated values are
usually determined at 298.15 K and denoted S°298
Standard entropy change (ΔS°) - change in entropy for a reaction calculated using the standard
entropies, usually at room temperature and denoted ΔS°298
Standard free energy change (ΔG°) - change in free energy for a process occurring under standard
conditions (1 bar pressure for gases, 1 M concentration for
solutions)
Standard free energy of formation (ΔGf °) - change in free energy accompanying the formation of one mole of
substance from its elements in their standard states
Standard molar volume - volume of 1 mole of gas at STP, approximately 22.4 L for gases
behaving ideally
Stoichiometric factor ratio of coefficients in a balanced chemical equation, used in
computations relating amounts of reactants and products
Stoichiometry - relationships between the amounts of reactants and products of a
chemical reaction
Strong acid - acid that reacts completely when dissolved in water to yield
hydronium ions
Strong base - base that reacts completely when dissolved in water to yield
hydroxide ions
Strong electrolyte - substance that dissociates or ionizes completely when dissolved in
water
Structural formula - shows the atoms in a molecule and how they are
connected
Structural isomer - one of two substances that have the same molecular formula but
different physical and chemical properties because their atoms are bonded
differently
Supersaturated - of concentration that exceeds solubility; a nonequilibrium
state
Surroundings - all matter other than the system being studied
System - portion of matter undergoing a chemical or physical change being
studied
Temperature - intensive property of matter that is a quantitative measure of
“hotness” and “coldness”
Tetrahedral - shape in which four outside groups are placed around a central atom
such that a three-dimensional shape is generated with four corners and 109.5°
angles between each pair and the central atom
Theory - well-substantiated, comprehensive, testable explanation of a
particular aspect of nature
Thermal energy - kinetic energy associated with the random motion of atoms and
molecules
Thermochemistry - study of measuring the amount of heat absorbed or released during a
chemical reaction or a physical change
Third law of thermodynamics - entropy of a perfect crystal at absolute zero (0 K) is
zero
Titration analysis - quantitative chemical analysis method that involves measuring the
volume of a reactant solution required to completely react with the analyte in a
sample
Titration is a procedure for carrying out a chemical reaction between two
solutions by the controlled addition (from a buret) of one solution to the
other. In a titration a means must be found, as by the use of an indicator,to
locate the equivalence point.
Transition metal - element in columns 3–11
Triple bond - bond in which three pairs of electrons are shared between two
atoms
Unified atomic mass unit (u) - alternative unit equivalent to the atomic mass
unit
Unsaturated - of concentration less than solubility
Valence bond theory description of bonding that involves atomic orbitals overlapping to
form σ or π bonds, within which pairs of electrons are
shared
Valence electrons - electrons in the outermost or valence shell (highest value of
n) of a ground-state atom; determine how an element
reacts
Van der Waals equation - modified version of the ideal gas equation containing additional
terms to account for nonideal gas behavior
Voltaic (galvanic) cell is an electrochemical cell in which a spontaneous chemical
reaction produces electricity.
Volume - amount of space occupied by an object
Volume percentage - ratio of solute-to-solution volume expressed as a
percentage
Wavefunction (ψ) - mathematical description of an atomic orbital that describes the
shape of the orbital; it can be used to calculate the probability of finding the
electron at any given location in the orbital, as well as dynamical variables
such as the energy and the angular momentum
Wavelength (λ) - distance between two consecutive peaks or troughs in a
wave
Weak acid - acid that reacts only to a slight extent when dissolved in water to
yield hydronium ions
Weak base - base that reacts only to a slight extent when dissolved in water to
yield hydroxide ions
Weak electrolyte - substance that ionizes only partially when dissolved in
water
Weight - force that gravity exerts on an object
Work (w) - energy transfer due to changes in external, macroscopic variables
such as pressure and volume; or causing matter to move against an opposing
force
σ bonding orbital - molecular orbital in which the electron density is found along the
axis of the bond