Hi-Q Chemistry
change of state
a change of a substance from one state to another
conjugate acid
in a conjugate acid-base pair, the species can donate a proton
heat
the energy that flows into or out of a system because of a difference in temperature between the thermodynamic system and its surroundings
mass
the quantity of matter in a material
coordinate covalent bond
a bond formed when both electrons of the bond are donated by one atom
chemical property
a characteristic of a material involving its chemical change
covalent bond
a chemical bond formed by the sharing of a pair of electrons between atoms
complete ionic equation
a chemical equation in which strong electrolytes (such as soluble ionic compounds) are written as separate ions in the solution
molecular equation
a chemical equation in which the reactants and products are written as if they were molecular substances, even though they may actually exist in solutions as ions
molecular formula
a chemical formula that gives the exact number of different atoms of an element in a molecule
high-spin complex ion
a complex ion in which there is minimum pairing of electrons in the orbitals of metal atom
low-spin complex ion
a complex ion in which there is more pairing electrons in the orbitals of the metal atom than in a corresponding high-spin complex ion
ionic compound
a compound composed of cations and anions
particle accelerator
a device used to accelerate electrons, protons, and alpha particles and other ions to very high speeds
concentration
a general term referring to the quantity of solute in a standard quantity of solvent or solution
exchange (metathesis) reaction
a reaction between compounds that, when written as a molecular equation, appears to involve the exchange of parts between the two reactants
decomposition reaction
a reaction in which a single compound reacts to give two or more substances
acid salt
a salt that has an acidic hydrogen atom and can undergo neutralization with basics
chain reaction, nuclear
a self-sustaining series of nuclear fissions caused by the absorption of neutrons released from previous nuclear fisisions
hypothesis
a tentative explanation of some regularity of nature
gravimetric analysis
a type of quantitative analysis in which the amount of a species in a material is determined by converting the species to a product that can be isolated completely and weighed
atmosphere (atm)
a unit of pressure equal to exactly 760 mmHg; 1 atm = 101.325 kPa (exact)
liter (L)
a unit of volume equal to a cubic decimeter (equal to approximately one quart)
monatomic ion
an ion formed from a single atom
alpha emission
emission of a 4,2He nucleus, or alpha particle, from an unstable nucleus
miscible fluids
fluids that mix with or dissolve in each other in all proportions
optically active
having the ability to rotate the plane of light waves, either as a pure substance or in a solution
geometric isomers
isomers in which the atoms are joined to one another in the same way but differ because some atoms occupy different relative positions in space
ionization isomers
isomers of a complex that differ in the anion that is coordinated to the metal atom
antibonding orbitals
molecular orbitals having zero values in the region between two nuclei and therefore concentrated in other regions
heteronuclear diatomic molecules
molecules composed of two different nuclei
homonuclear diatomic molecules
molecules composed of two like nuclei
mass percentage
parts per hundred parts of the total, by mass
hydronium ion
the H3O+ ion; also called the hydrogen ion and written H+ (aq)
deposition
the change of a vapor to a solid
nitrogen cycle
the circulation of the element nitrogen in the biosphere, from nitrogen fixation to the release of free nitrogen by denitrifying bacteria
molar gas constant (R)
the constant of proportionality relating the molar volume of a gas to T/P
fuel rods
the cylinders that contain fissionable material for a nuclear reactor
alkali metals
the group IA elements; they are reactive metals
atomic number (Z)
the number of protons in the nucleus of an atom
partial pressure
the pressure exerted by a particular gas in a mixture
coagulation
the process by which the dispersed phase of a colloid is made to aggregate and thereby separate from the continuous phase
inner-transition elements
the two rows of elements at the bottom of the periodic table; the elements with a partially filled f subshell in common oxidation states
binary compound
a compound composed of only two elements
calorie (cal)
a non-SI unit of energy commonly used by chemists, originally defined as the amount of energy needed to raise the temperature of 1 g of water by 1 degree Celsius; equal to 4.184 J
atomic symbol
a one- or two-letter notation used to represent an atom corresponding to a particular element
cation
a positively charged ion
chemical vapor deposition
a process in which a chemical reaction in a gas or vapor produces a product that can be deposited onto a solid material or substrate
combination reaction
a reaction in which two substances combine to form a third substance
buffer
a solution characterized by the ability to resist changes in pH when limited amounts of acid or base are added to it
amphiprotic species
a species that can act as either an acid or a base (that is, it can lose or gain a proton)
chemical bond
a strong attractive force that exists between certain atoms in a substance
acid
a substance that produces hydrogen ions, H-, (hydronium ion, H3O+) when it dissolves in water; the species (molecule or ion) that donates a proton to another species in a proton-transfer reaction
base
a substance that produces hydroxide ions, OH-, when it dissolves in water; the species (molecule or ion) that accepts proton in a proton-transfer reaction
alkaline dry cell
a voltaic cell that is similar to the Lechanche dry cell but uses potassium hydroxide in place of ammonium chloride
complex ion
an ion formed from a metal ion with a Lewis base attached to it by a coordinate covalent bond
activated complex (transition state)
an unstable grouping of atoms that can break up to form products
chiral
possessing the quality of handedness; has a mirror image that is not identical to the object
colligative properties
properties that depend on the concentration of solute molecules or ions in a solution but not on the chemical identity of the solute
mole (mol)
the quantity of a given substance that contains as many molecules or formula units as the number of atoms in exactly 12 g of carbon-12; the amount of substance containing Avogadro's number of molecules or formula units
ion exchange
a process in which a water solution is passed through a column of a material that replaces one kind of ion in solution with another kind
dipole moment
a quantitative measure of the degree of charge separation in a molecule
excited state
a quantum-mechanical state of an atom or molecule associated with any energy level except the lowest, which is the ground state
ground state
a quantum-mechanical state of an atom or molecule associated with the lowest energy level
displacement reaction (single-replacement reaction)
a reaction in which an element reacts with a compound, displacing an element from it
oxidation-reduction reaction (redox reaction)
a reaction in which electrons are transferred between species or in which atoms change oxidation number
condensation reaction
a reaction in which two molecules or ions are chemically joined by the elimination of a small molecule such as water
neutralization reaction
a reaction of an acid and a base that results in an ionic compound and possibly water
functional group
a reactive portion of a molecule that undergoes predictable reactions
messenger RNA
a relatively small RNA molecule that can diffuse about the cell and attach itself to a ribosome, where it serves as a pattern for protein synthesis
homologous series
a series of compounds in which one compound differs from a preceding one by a fixed group of atoms, for example a -CH2- group
elementary reaction
a single molecular event, such as a collision of molecules, resulting in a reaction
crystalline solid
a solid composed of one or more crystals; each crystal has a well-defined ordered structure in three dimensions
covalent network solid
a solid that consists of atoms held together in large networks or chains by covalent bonds
molecular solid
a solid that consists of atoms or molecules held together by intermolecular forces
metallic solid
a solid that consists of positive cores of atoms held together by a surrounding "sea" of electrons (metallic bonding)
laser
a source of intense, highly directed beam of monochromatic light; light amplification by stimulated emission of radiation
lewis base
a species that can form a covalent bond by donating an electron pair to another species
oxidizing agent
a species that oxidizes another species; it is itself reduced
continuous spectrum
a spectrum containing light of all wavelengths
line spectrum
a spectrum showing only certain colors or specific wavelengths of light
compound
a substance composed of two or more elements chemically combined; a type of matter composed of atoms of two or more elements chemically combined in fixed proportions
nonelectrolyte
a substance, such as sucrose, or table sugar (C12H22O11), that dissolves in water to give a nonconducting or very poorly conducting solution
nuclide symbol
a symbol for a nuclide, in which the atomic number is given as a left subscript and the mass number is given as a left superscript to the symbol of the element
lewis electron-dot symbol
a symbol in which the electrons in the valence shell of an atom or ion are represented by dots placed around the letter symbol of the element
nuclear equation
a symbolic representation of a nuclear reaction
electrochemical cell
a system consisting of electrodes that dip into an electrolyte and in which a chemical reaction either uses or generates an electric current
isotope dilution
a technique to determine the quantity of a substance in a mixture or the total volume of solution by adding a known amount of an isotope to it
free energy
a thermodynamic quantity defined by the equation G=H-TS
coordination number
in a crystal, the number of nearest-neighbor atoms of an atom; in a complex, the total number of bonds the metal atom forms with ligands
metal refining
in metallurgy, the purification of a metal
coordination isomers
isomers consisting of complex cations and complex anions that differ in the way the ligands are distributed between the metal atoms
linkage isomers
isomers of a complex that differ in the atom of a ligand that is bonded to the metal atom
hydrate isomers
isomers of a complex that differ in the placement of water molecules in the complex
optical isomers (enantiomers)
isomers that are nonsuperimposable mirro images of one another
first ionization energy
the minimum energy needed to remove the highest-energy (that is, the outermost) electron from a neutral atom in the gaseous state
molar concentration (molarity)
the moles of solute dissolved in one liter of solution
molality
the moles of solute per kilogram of solvent
hydrologic cycle
the natural cycle of water from the oceans to fresh water source and back to the oceans
oxidation potential
the negative of the standard electrode potential
number of significant figures
the number of digits reported for the value of a measured or calculated quantity, indicating the precision of the value
molecularity
the number of molecules on the reactant side of an elementary reaction
magic number
the number of nuclear particles in a completed shell of protons or neutrons
frequency (v)
the number of wavelengths of a wave that pass a fixed point in one unit of time (usually one second)
oxidation
the part of an oxidation-reduction reaction in which there is a loss of electrons by a species (or an increase in the oxidation number of an atom)
electron configuration
the particular distribution of electrons among available subshells
mass percentage of solute
the percentage of mass of solute contained in a solution
osmosis
the phenomenon of solvent flow through a semipermeable membrane to equalize the solute concentrations on both sides of the membrane
equivalence point
the point in a titration when a stoichiometric amount of reactant has been added
half-cell
the portion of an electrochemical cell in which a half-reaction takes place
electrolysis
the process of producing a chemical change in an electrolytic cell
diffusion
the process whereby a gas spreads out through another gas to occupy the space uniformly
ion product
the product of ion concentrations in a solution, each concentration raised to a power equal to the number of ions in the formula of the ionic compound
electron volt (eV)
the quantity of energy that would have to be imparted to an electron (whose charge is 1.602 x 10^-19 C) to accelerate it by one volt potential difference
heat capacity
the quantity of heat needed to raise the temperature of a sample of substance one degree Celsius (or one kelvin)
magnetic quantum number
the quantum number that distinguishes orbitals of given n and l - that is, of given energy and shape - but having a different orientation in space; the allowed values are the integers from -l to +l
electromagnetic spectrum
the range of frequencies or wavelengths of electromagnetic radiation
cathode rays
the rays emitted by the cathode (negative electrode) in a gas discharge tube (tube of low-pressure gas through which an electric current is discharged)
limiting reactant
the reactant that is entirely consumed when a reaction goes to completion
hydrolysis
the reaction of an ion with water to produce the conjugate acid and hydroxide ion or the conjugate base and hydrogen ions
dissociation constant of a complex ion
the reciprocal, or inverse, value of the formation constant
band of stability
the region in which stable nuclides lie in a plot of number of protons against number of neutrons
metallurgy
the scientific study of the production of metals from their ores and the making of alloys having various useful properties
crystal systems
the seven basic shapes possible for unit cells; a classification of crystals
monomer
the small molecules that are linked together to form a polymer; a compound used to make a polymer (and from which the polymer's repeating unit arises)
critical mass
the smallest mass of fissionable material in which a chain reaction can be sustained
formula weight (FW)
the sum of the atomic weight of all atoms in a formula unit of a compound
molecular weight
the sum of the atomic weights of all the atoms in a molecule
internal energy
the sum of the kinetic and the potential energies of the particles making up a system
overall order of a reaction
the sum of the orders of the reactant species in the rate law
frequency factor
the symbol A in the Arrhenius equation, assumed to be a constant
fractional precipitation
the technique of separating two or more ions from a solution by adding a reactant that precipitates first one ion, then another, and so forth
critical temperature
the temperature above which the liquid state of a substance no longer exists regardless of the pressure
melting point
the temperature at which a crystalline solid changes to a liquid
freezing point
the temperature at which a pure liquid changes to a crystalline solid, or freezes
kinetic molecular theory
the theory that a gas consists of molecules in constant random motion
half-life
the time it takes for the reactant concentration to decrease one-half of its initial value; the time it takes for one-half of the nuclei in a sample to decay
mass defect
the total nucleon mass minus the atomic mass of a nucleus
mass number (A)
the total number of protons and neutrons in a nucleus
homogeneous catalysis
the use of a catalyst in the same phase as the reacting species
equilibrium constant Kc
the value obtained for the equilibrium constant expression when equilibrium concentrations are substituted
critical pressure
the vapor pressure at the critical temperature; the minimum pressure that must be applied to a gas at the critical temperature to liquefy it
molar gas volume
the volume of one mole of gas
chlor-alkali membrane cell
a cell for the electrolysis of aqueous sodium chloride in which the anode and cathode compartments are separated by a special plastic membrane that allows only cations to pass through it
gas chromatography
a chromatographic separation method in which a gaseous mixture of vaporized substances is separated into its components by passing the mixture through a column of packing material; substances in the mixture are attracted to the packing material to different extents and thus move through the column at different rates
boiling-point elevation
a colligative property of a solution equal to the boiling point of the solution minus the boiling point of the pure solvent
freezing-point depression
a colligative property of a solution equal to the freezing point of the pure solvent minus the freezing point of the solution
osmotic pressure
a colligative property of a solution equal to the pressure that, when applied to the solution, just stops osmosis
nuclear bombardment reaction
a nuclear reaction in which a nucleus is bombarded, or struck, by another nucleus or by a nuclear particle
nuclear fusion
a nuclear reaction in which light nuclei combine to give a stabler, heavier nucleus plus possibly several neutrons, and energy is released
metastable nucleus
a nucleus in an excited state with a lifetime of at least one nanosecond
exact number
a number that arises when you count items or sometimes when you define a unit
flotation
a physical method of separating a mineral from the gangue that depends on differences in their wettabilities by a liquid solution
acid-base titration curve
a plot of the pH of a solution of acid (or base) against the volume of added base (or acid)
copolymer
a polymer consisting of two or more different monomer units
condensation polymer
a polymer formed by linking many molecules together by condensation reactions
addition polymer
a polymer formed by linking together many molecules by addition reactions
metal
a substance or mixture that has a characteristic luster, or shine, is generally a good conductor of heat and electricity, and is malleable and ductile
element
a substance that cannot be decomposed by any chemical reaction into simpler substances; a type of matter composed of only one kind of atom, each atom of a given kind having the same properties; a substance whose atoms al have the same atomic number
catalyst
a substance that increases the rate of reaction without being consumed in the overall reaction
molecular substance
a substance that is composed of molecules, all of which are alike
metaphosphoric acids
acids with the general formula (HPO3)n
homogeneous equilibrium
an equilibrium that involves reactants and products in a single phase
atomic theory
an explanation of the structure of matter in terms of different combinations of very small particles (atoms)
equilibrium-constant expression
an expression obtained for a reaction by multiplying the concentrations of products, dividing by the concentrations of reactants, and raising each concentration term to a power equal to the coefficient in the chemical equation
enthalpy
an extensive property of a substance that can be used to obtain the heat absorbed or evolved in a chemical reaction at constant pressure; equals the quantity U + PV
actinides
elements in the last of the two rows at the bottom of the periodic table; the 14 elements following actinium in the periodic table, in which the 5f subshell is filling
gamma emission
emission from an excited nucleus of a gamma photon, corresponding to radiation with a wavelength of about 10^-12 m
beta emission
emission of a high-speed electron from an unstable nucleus
fuel cell
essentially a battery, but it differs by operating with a continuous supply of energetic reactants or fuel
immiscible fluids
fluids that do not mix but form separate layers
conjugate base
in a conjugate acid-base pair, the species that can accept a proton
deuterons
nuclei of hydrogen-2 atoms
pascal
the SI unit of pressure 1 Pa = 1 kg / (m * s2)
percentage yield
the actual yield (experimentally determined) expressed as a percentage of the theoretical yield (calculated)
nucleus
the atom's central core; it has most of the atom's mass and one or more units of positive charge
hydration
the attraction of ions for water molecules
ampere (A)
the base unit of current in the International system (SI)
lattice energy
the change in energy that occurs when an ionic solid is separated into isolated ions in the gas phase
enthalpy of reaction
the change in enthalpy for a reaction at a given temperature and pressure; equals the heat of reaction at constant pressure
anion
a negatively charged ion
angular momentum quantum number (l)
also known as the azimuthal quantum number; the quantum number that distinguishes orbitals of given n having different shapes; it can have any integer value from 0 to n-1
bimolecular reaction
an elementary reaction that involves two reactant molecules
basic oxide
an oxide that reacts with acids
bonding orbitals
molecular orbitals that are concentrated in regions between nuclei
ceramics
nonmetallic, inorganic solids that are hard and brittle and usually produced at elevated temperature
atomic weight
the average atomic mass for the naturally occurring element, expressed in atomic mass units
Avogadro's number
the number of atoms in a 12-g sample of carbon-12, equal to 6.02 x 10^23 to three significant figures
calorimeter
a device used to measure the heat absorbed or evolved during a physical or chemical change
chromatography
a name given to a group of similar separation techniques that depend on how fast a substance moves, in a stream of gas or liquid, past a stationary phase to which the substance may be slightly attracted
addition reaction
a reaction in which parts of a reactant are added to each carbon atom of a carbon-carbon double bond, which becomes a C-C single bond
combustion reaction
a reaction of a substance with oxygen, usually with the rapid release of heat to produce a flame
codon
a sequence of three bases in a messenger RNA molecule that serves as the code for a particular amino acid
amorphous solid
a solid that has a disordered structure; it lacks the well-defined arrangement of basic units (atoms, molecules, or ions) found in a crystal
absolute temperature scale
a temperature scale in which the lowest temperature that can be attainted theoretically is zero
amphoteric oxide
an oxide that has both acidic and basic properties
acidic oxide
an oxide that reacts with bases
catenation
the covalent bonding of two or more atoms of the same element to one another
anode
the electrode at which oxidation occurs
binding energy
the energy needed to break a nucleus into its individual protons and neutrons
acid-ionization constant (Ka)
the equilibrium constant for the ionization of a weak acid
cell reaction
the net reaction that occurs in a voltaic cell
activity of a radioactive source
the number of nuclear disintegrations per unit time occurring in a radioactive material
common-ion effect
the shift in an ionic equilibrium caused by the addition of a solute that provides an ion that takes part in the equilibrium
bond order
in a Lewis formula, the number of pairs of electrons in a bond. In molecular orbital theory, one-half the difference between the number of bonding electrons and the number of anti bonding electrons
activity series
a listing of the elements in order of their ease of losing electrons during reactions in aqueous solutions
atomic mass unit (amu)
a mass unit equal to exactly one-twelfth the mass of a carbon-12 atom
alloy
a material with metallic properties that is either a compound or a mixture
amphoteric hydroxide
a metal hydroxide that reacts with both acids and bases
Claus process
a method of obtaining free sulfur by the partial burning of hydrogen sulfide
bent geometry
nonlinear molecular geometry, in the case of a molecule of three atoms
complementary bases
nucleotide bases that form strong hydrogen bonds with one another
acid rain
rain having a pH lower than that of natural rain, which has a pH of 5.6
base-ionization constant
the equilibrium constant for the ionization of a weak base
base pairing
the hydrogen bonding of complementary bases
catalysis
the increase in rate of a reaction as the result of the addition of a catalyst
chemical equation
the symbolic representation of a chemical reaction in terms of chemical formulas
chemical nomenclature
the systematic naming of chemical compounds
glass electrode
a compact electrode used to determine pH by emf measurements
face-centered cubic unit cell
a cubic unit cell in which there are lattice points at the centers of each face of the unit cell in addition to those at the corners
manometer
a device that measures the pressure of a gas or liquid in a sealed vessel
nuclear fission reactor
a device that permits a controlled chain reaction of nuclear fissions
crystal
a kind of solid having a regular three-dimensional arrangement of atoms, molecules, or ions
ligand
a lewis base that bonds to a metal ion to form a complex ion
mixture
a material that can be separated by physical means into two or more substances
electronegativity
a measure of the ability of an atom in a molecule to draw bonding electrons to itself
heterogeneous mixture
a mixture that consists of physically distinct parts, each with different properties
linear geometry
a molecular geometry in which all atoms line up along a straight line
angstrom
a non-SI unit of length; 1 A = 10^-10 m
nuclear fission
a nuclear reaction in which a heavy nucleus splits into lighter nuclei and energy is released
neutron
a particle found in the nucleus of an atom; it has mass almost identical to that of a proton but no electric charge
gene
a sequence of nucleotides in a DNA molecule that codes for a given protein
ionic solid
a solid that consists of cations and anions held together by the electrical attraction of opposite charges (ionic bonds)
ideal solution
a solution of two or more substances each of which follows Raoult's law
lewis acid
a species that can form a covalent bond by accepting an electron pair from another species
nuclear force
a strong force of attraction between nucleons that acts only at very short distances
condensed (structural) formula
a structural formula in which the bonds around each carbon atom is not explicitly written
moderator
a substance that slows down neutrons in a nuclear fission reactor
electrolyte
a substance, such as sodium chloride, that dissolves in water to give an electrically conducting solution
entropy
a thermodynamic quantity that is a measure of ow dispersed the energy of a system is among the different possible ways that a system can contain energy
delocalized bonding
a type of bonding in which a bonding pair of electrons is spread over a number of atoms rather than localized between two
Curie (Ci)
a unit of activity, equal to 3.700 x 10^10 disintegrations per second
ion
an electrically charged particle obtained from an atom or a chemically bonded group of atoms by adding or removing electrons
metalloid (semimetal)
an element having both metallic and nonmetallic properties
polyatomic ion
an ion consisting of two or more atoms chemically bonded together and carrying a net electric charge
net ionic equation
an ionic equation from which spectator ions have been canceled
experiment
an observation of natural phenomena carried out in a controlled manner so that the results can be duplicated and rational conclusions obtained
material
any particular kind of matter
nitrogen-fixing bacteria
bacteria that can produce nitrogen compounds in the soil from atmospheric nitrogen
constitutional (structural) isomers
isomers that differ in how the atoms are joined together; compounds with the same molecular formula but different structural formulas
phase
one of several different homogeneous materials present in the portion of matter under study
equatorial direction
one of the three directions pointing from the center of a trigonal bipyramid to a vertex other than one on the axis
axial direction
one of two directions pointing from the center of a trigonal bipyramid along its axis
allotrope
one of two or more distinct forms of an element in the same physical state
half-reaction
one of two parts of an oxidation-reduction reaction, one part of which involves a loss of electrons (or increase of oxidation number) and the other a gain of electrons (or decrease of oxidation number)
hybrid orbitals
orbitals used to describe bonding that are obtained by taking combinations of atomic orbitals of the isolated atoms
photon
particle of electromagnetic energy with energy E proportional to the observed frequency of light E = hv
mole percent
percent, in terms of moles, of a component in a solution; obtained by multiplying mole fraction by 100
levorotatory
refers to a compound whose solution rotates the plane of polarized light to the left (when looking toward the source of light)
dextrorotatory
refers to a compound whose solution rotates the plane of polarized light to the right (when looking toward the source of light)
isoelectronic
refers to different species having the same number and configuration of electrons
desalinate
remove ions from brackish (slightly salty) water or seawater, to make drinkable or industrially usable water
monosaccharides
simple sugars, each containing three to nine carbon atoms, generally all but one of which bear a hydroxyl group, the remaining one being part of a carbonyl group
energy levels
specific energy values in an atom
noble gases
the Group VIIIA elements; all are gases consisting of uncombined atoms; relatively unreactive elements
kilogram (kg)
the SI base unit for mass; equal to about 2.2 pounds
meter (m)
the SI base unit of length
kelvin (K)
the SI base unit of temperature; a unit on an absolute temperature scale
liquid
the form of matter that is a relatively incompressible fluid; fixed volume but no fixed shape
gas
the form of matter that is an easily compressible fluid; a given quantity will fit into a container of almost any size and shape
empirical formula (simplest formula)
the formula of a substance written with the smallest integer (whole number) subscripts
degree of ionization
the fraction of molecules that react with water to give ions
effective nuclear charge
the positive charge that an electron experiences from the nucleus, equal to the nuclear charge but reduced by any shielding or screening from any intervening electron distribution
energy
the potential or capacity to move matter
effusion
the process in which a gas flows through a small hole in a container
distillation
the process in which a liquid is vaporized and condensed; used to separate substances of different volatilities
liquefaction
the process in which a substance that is normally a gas changes to the liquid state
doping
the process of adding small quantities of other elements to a semiconducting element
celsius scale
the temperature scale in general scientific use; there are exactly 100 units between the freezing point and the normal boiling point of water
octet rule
the tendency of atoms in molecules to have eight electrons in their valence shells (two for hydrogen atoms)
heterogeneous catalysis
the use of a catalyst that exists in a different phase from the reacting species, usually a solid catalyst in contact with a gaseous or liquid solution of reactants
chemical formula
a notation that uses atomic symbols with numerical subscripts to convey the relative proportions of atoms of the different elements in a substance
chlor-alkali mercury cell
a cell for the electrolysis of aqueous sodium chloride in which mercury metal is used as the cathode
chemical reaction
a change in which one or more kinds of matter are transformed into a new kind of matter or several new kinds of matter; the rearrangement of the atoms present in the reacting substances to give new chemical combinations present in the substances formed by the reaction
complex (coordination compound)
a compound consisting either of complex ions and other ions of opposite charge or of a neutral complex species
alcohol
a compound obtained by substituting a hydroxyl group (-OH) for an -H atom on a tetrahedral (sp3 hybridized) carbon atom of a hydrocarbon group
body-centered cubic unit cell
a cubic unit cell in which there is a lattice point at the center of the unit cel as well as at the corners
barometer
a device for measuring the pressure of he atmosphere
colloid
a dispersion of particles of one substance (the dispersed phase) throughout another substance or solution (the continuous phase)
acid-base indicator
a dye used to distinguish between acidic and basic solutions by means of the color changes it undergoes in these solutions
chemical equilibrium
the state reached by a reaction mixture when the rates of forward and reverse reactions have become equal
chemical kinetics
the study of how reaction rates change under varying conditions and of what molecular events occur during the overall reaction
boiling point
the temperature at which the vapor pressure of a liquid equals the pressure exerted on the liquid (atmospheric pressure, unless the vessel containing the liquid is closed)
mineral
a naturally occurring inorganic solid substance or solid solution with definite crystalline form
phospholipid bilayer
a part of a biological membrane consisting of two layers of phospholipid molecules
International System of Units (SI)
a particular choice of metric units that was adopted by the General Conference of Weights and Measures in 1960
molar mass
the mass of one mole of substance; in grams, it is numerically equal to the formula weight in atomic mass units
density
the mass per unit volume of a substance or solution
percentage composition
the mass percentages of each element in a compound
electromotive force (emf)
the maximum potential difference between the electrodes of a voltaic cell
dimensional analysis
the method of calculation in which one carries along the units for quantities
formal charge
(of an atom in a Lewis formula) the hypothetical charge you obtain by assuming that bonding electrons are equally shared between bonded atoms and that electrons of each lone pair belong completely to one atom
ionic bond
a chemical bond formed by the electrostatic attraction between positive and negative ions
downs cell
a commercial electrochemical cell used to obtain sodium metal by the electrolysis of molten sodium chloride
coordination compound
a compound consisting either of complex ions and other ions of opposite charge or of a neutral complex species
hydrate
a compound that contains water molecules weakly bound in its crystal
initiator
a compound that produces free radicals in a reaction for the preparation of an addition polymer
nonstoichiometric compound
a compound whose composition varies from its idealized formula
law
a concise statement or mathematical equation about a fundamental relationship or regularity of nature
polar covalent bond
a covalent bond in which the bonding electron spend more time near one atom than near the other
double bond
a covalent bond in which two pairs of electrons are shared by two atoms
hexagonal close-packed structure (hcp)
a crystal structure composed of close-packed atoms (or other units) with the stacking ABABABA...; the structure has a hexagonal unit cell
cubic close-packed structure (ccp)
a crystal structure composed of close-packed atoms (or other units) with the stacking ABCABCABCA...; it has a face-centered cubic unit cell
molecule
a definite group of atoms that are chemically bonded together - that is, tightly connected by attractive forces
orbital diagram
a diagram to show how the orbitals of a subshell are occupied by electrons
conversion factor
a factor equal to 1 that converts a quantity expressed in one unit to a quantity expressed in another unit
lewis electron-dot formula
a formula using dots to represent valence electrons
phase diagram
a graphical way to summarize the conditions under which the different states of a substance are stable
monodentate ligand
a ligand that bonds to a metal atom through one atom of the ligand
ionic radius
a measure of the size of the spherical region around the nucleus of an ion within which the electrons are most likely to be found
homogeneous mixture
a mixture that is uniform in its properties throughout given samples
cyclotron
a type of particle accelerator consisting of two hollow, semicircular metal electrodes, called dees (because the shape resembles the letter D), in which charged particles reaccelerated by stages to higher and higher kinetic energies; ions introduced at the center are accelerated in the space between the two dees
millimeters of mercury (mmHg)
a unit of pressure also known as the torr; equal to that exerted by a column of mercury 1 mm high at zero degrees Celsius
electron
a very light, negatively charged particle that exists in the region around the atom's positively charged nucleus
nickel-cadmium cell
a voltaic cell consisting of an anode of cadmium and a cathode of hydrated nickel oxide (approximately NiOOH) on nickel; the electrolyte os potassium hydroxide
lithium-iodine battery
a voltaic cell in which the anode is lithium metal and the cathode is an I2 complex
lead storage cell
a voltaic cell that consists of electrodes of lead alloy grids; one electrode is packed with a spongy lead to form the anode, and the other is packed with lead dioxide to form the cathode
atomic orbital
a wave function for an electron in an atom; pictured qualitatively by describing the region of space where there is a high probability of finding the electron
hydrogen bonding
a weak to moderate attractive force that exists between a hydrogen atom covalently bonded to a very electronegative atom and a lone pair of electrons on another small, electronegative atom; represented in formulas by a series of dots
physical adsorption
adsorption in which the attraction is provided by weak intermolecular forces
matter
all of the objects around you; whatever occupies space and can be perceived by our senses
neutron activation analysis
an analysis of elements in a sample based on the conversion of stable isotopes to radioactive isotopes by bombarding a sample with neutrons
nanotechnology
an area of technology in which one manipulates materials on a molecular scale to create useful devices
dipole-dipole force
an attractive intermolecular force resulting from the tendency of polar molecules to align themselves such that the positive end of one molecule is near the negative end of another
electrolytic cell
an electrochemical cell in which an electric current drives an otherwise non spontaneous reaction
ion-selective electrode
an electrode whose emf depends on the concentration of a particular ion in solution
bonding pair
an electron pair shared between two atoms
lone pair
an electron pair that remains on one atom and is not shared
main-group element
an element in an A column of the periodic table, in which an outer s or p subshell is filling
nonmetal
an element that does not exhibit the characteristics of a metal
equilibrium constant Kp
an equilibrium constant for a gas reaction, similar to Kc, but in which concentrations of gases are replaced by partial pressures (in atm)
heterogeneous equilibrium
an equilibrium involving reactants and products in more than one phase
atom
an extremely small particle of matter that retains its identity during chemical reactions
noble gas core
an inner-shell configuration corresponding to one of the noble gases
mass spectrometer
an instrument, such as one based on Thomson's principles, that measures the masse-to-charge ratios of atoms
isotopes
atoms whose nuclei have the same atomic number but different mass numbers; that is, the nuclei have the same number of protons but different numbers of neutrons
denitrifying bacteria
bacteria that use nitrate ion NO3-, as a source of energy; they convert the ion to gaseous nitrogen
lipids
biological substances like fats and oils that are soluble in organic solvents, such as chloroform and carbon tetrachloride
inorganic compounds
compounds composed of elements other than carbon, excluding carbon monoxide, carbon dioxide, carbonates, and cyanides
hydrocarbons
compounds containing only carbon and hydrogen
isomers
compounds of the same molecular formula but with different arrangements of the atoms
organic compounds
compounds that contain carbon combined with other elements, such as hydrogen, oxygen, and nitrogen
control rods
cylinders composed of substances that absorb neutrons, such as boron cadmium, and can therefore slow a nuclear chain reaction
oxidation number (oxidation state)
either the actual charge on an atom in a substance, if the atom exists as a monatomic ion, or a hypothetical charge assigned by simple rules
joule (J)
the SI unit of energy; 1 J = 1 kg * m2/s2
bond energy
the average enthalpy change for the breaking of a bond in a molecule in the gas phase
chemisorption
the binding of a species to a surface by chemical bonding forces
adsorption
the binding or attraction of molecules to a surface
condensation
the change of a gas to either the liquid or the solid state
freezing
the change of a liquid to the solid state
melting (fusion)
the change of a solid to the liquid state
Hall-Heroult process
the commercial method for producing aluminum by the electrolysis of a molten mixture of aluminum oxide in cryolite, Na3AlF6
electron capture
the decay of an unstable nucleus by capturing, or picking up, an electron from an inner orbital of atom
crystal field splitting
the difference in energy between the two sets of d orbitals on a central metal ion that arises from the interaction of the orbitals with the electric field of the ligands
bond length (bond distance)
the distance between the nuclei in a bond
photoelectric effect
the ejection of electrons from the surface of a metal or other material when light shines on it
group (of the periodic table)
the elements in any one column of the periodic table
period
the elements in any one horizontal row of the periodic table
f-block transition elements (inner transition elements)
the elements with a partially filled f subshell in common oxidation states
kinetic energy
the energy associated with an object by virtue of its motion
electron affinity
the energy change for the process of adding an electron to a neutral atom in the gaseous state to form a negative ion
ionization energy
the energy needed to remove an electron from an atom (or molecule)
pairing energy
the energy required to put two electrons into the same orbital
formation constant (stability constant) of a complex ion Kf
the equilibrium constant for the formation of a complex ion from the aqueous metal ion and the ligands
ion-product constant for water
the equilibrium value of the ion product [H3O+][OH-]
lanthanides
the first of the two rows of elements at the bottom of the periodic table; the 14 elements following lanthanum in the periodic table, in which the 4f subshell is filling
intermolecular forces
the forces of interaction between molecules
mole fraction
the fraction of moles of a component in the total moles of a mixture; the moles of a component substance divided by the total moles of solution
fractional (isotopic) abundance
the fraction of the total number of atoms that is composed of a particular isotope
molecular geometry
the general shape of a molecule, as determined by the relative positions of the atomic nuclei
crystal lattice
the geometric arrangement of lattice points of a crystal, in which we choose one lattice point at the same location within each of the basic units of the crystal
octahedral geometry
the geometry of a molecule in which six atoms occupy the vertices of a regular octahedron (a figure with eight faces and six vertices) with the central atom at the center of the octahedron
alkaline earth metals
the group IIA elements; they are reactive metals, though less reactive than the alkali metals
halogens
the group VIIA elements; they are reactive nonmetals
formula unit
the group of atoms or ions explicitly symbolized in the formula
heat of reaction
the heat absorbed (or evolved) during a chemical reaction; it equals the value of q required to return the chemical system to a given temperature at the completion of the reaction
heat of solution
the heat absorbed (or evolved) when an ionic substance dissolves in water
heat of fusion (enthalpy of fusion)
the heat needed for the melting of a solid
heat of vaporization
the heat needed for the vaporization of a liquid
deoxyribonucleic acid (DNA)
the hereditary constituent of cells; it consists of two polymer strands of deoxyribonucleotide units
London forces (dispersion forces)
the weak attractive forces between molecules resulting from the small, instantaneous dipoles that occur because of the varying positions of the electrons during their motion about nuclei
d-block transition elements
those transition elements with an unfilled d subshell in common oxidation states
conjugate acid-base pair
two species in an acid-base reaction, one acid and one base, that differ by the loss or gain of a proton
covalent radii
values assigned to atoms in such a way that the sum of covalent radii A and B predicts an approximate A-B bond length
