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