# Glossary

σ bonding orbital

molecular orbital in which the electron density is found along the axis of the bond

π bonding orbital

molecular orbital formed by side-by-side overlap of atomic orbitals, in which the electron density is found on opposite sides of the internuclear axis

σ* bonding orbital

antibonding molecular orbital formed by out-of-phase overlap of atomic orbital along the axis of the bond, generating a node between the nuclei

π* bonding orbital

antibonding molecular orbital formed by out of phase side-by-side overlap of atomic orbitals, in which the electron density is found on both sides of the internuclear axis, and there is a node between the nuclei

acid anhydride

compound that reacts with water to form an acid or acidic solution

acid ionization

reaction involving the transfer of a proton from an acid to water, yielding hydronium ions and the conjugate base of the acid

acid ionization constant (Ka)

equilibrium constant for an acid ionization reaction

acid-base indicator

weak acid or base whose conjugate partner imparts a different solution color; used in visual assessments of solution pH

acidic

a solution in which [H3O+] > [OH−]

actinide

inner transition metal in the bottom of the bottom two rows of the periodic table

actinide series

(also, actinoid series) actinium and the elements in the second row or the f-block, atomic numbers 89–103

active electrode

electrode that participates as a reactant or product in the oxidation-reduction reaction of an electrochemical cell; the mass of an active electrode changes during the oxidation-reduction reaction

alkali metal

element in group 1

alkaline battery

primary battery similar to a dry cell that uses an alkaline (often potassium hydroxide) electrolyte; designed to be an improved replacement for the dry cell, but with more energy storage and less electrolyte leakage than typical dry cell

alkaline earth metal

element in group 2

allotropes

two or more forms of the same element, in the same physical state, with different chemical structures

amorphous

solid material such as a glass that does not have a regular repeating component to its three-dimensional structure; a solid but not a crystal

amphiprotic

species that may either donate or accept a proton in a Bronsted-Lowry acid-base reaction

amphoteric

species that can act as either an acid or a base

anode

electrode in an electrochemical cell at which oxidation occurs

antibonding orbital

molecular orbital located outside of the region between two nuclei; electrons in an antibonding orbital destabilize the molecule

aqueous solution

solution for which water is the solvent

Aufbau principle

procedure in which the electron configuration of the elements is determined by “building” them in order of atomic numbers, adding one proton to the nucleus and one electron to the proper subshell at a time

autoionization

reaction between identical species yielding ionic products; for water, this reaction involves transfer of protons to yield hydronium and hydroxide ions

axial position

location in a trigonal bipyramidal geometry in which there is another atom at a 180° angle and the equatorial positions are at a 90° angle

base anhydride

metal oxide that behaves as a base towards acids

base ionization

reaction involving the transfer of a proton from water to a base, yielding hydroxide ions and the conjugate acid of the base

base ionization constant (Kb)

equilibrium constant for a base ionization reaction

basic

a solution in which [H3O+] < [OH−]

battery

single or series of galvanic cells designed for use as a source of electrical power

bicarbonate anion

salt of the hydrogen carbonate ion HCO3-

bidentate ligand

ligand that coordinates to one central metal through coordinate bonds from two different atoms

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.

bismuth

heaviest member of group 15; a less reactive metal than other representative metals

bond angle

angle between any two covalent bonds that share a common atom

bond dipole moment

separation of charge in a bond that depends on the difference in electronegativity and the bond distance represented by partial charges or a vector

bond distance

(also, bond length) distance between the nuclei of two bonded atoms

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

bond order

number of pairs of electrons between two atoms; it can be found by the number of bonds in a Lewis structure or by the difference between the number of bonding and antibonding electrons divided by two

bonding orbital

molecular orbital located between two nuclei; electrons in a bonding orbital stabilize a molecule

borate

compound containing boron-oxygen bonds, typically with clusters or chains as a part of the chemical structure

Born-Haber cycle

thermochemical cycle relating the various energetic steps involved in the formation of an ionic solid from the relevant elements

Brønsted-Lowry acid

proton donor

Brønsted-Lowry base

proton acceptor

buffer

mixture of appreciable amounts of a weak acid-base pair the pH of a buffer resists change when small amounts of acid or base are added

buffer capacity

amount of an acid or base that can be added to a volume of a buffer solution before its pH changes significantly (usually by one pH unit)

carbonate

salt of the anion CO_3^2- often formed by the reaction of carbon dioxide with bases

cathode

electrode in an electrochemical cell at which reduction occurs

cathodic protection

approach to preventing corrosion of a metal object by connecting it to a sacrificial anode composed of a more readily oxidized metal

cell notation (schematic)

symbolic representation of the components and reactions in an electrochemical cell

cell potential

difference in potential of the cathode and anode half-cells

central metal

ion or atom to which one or more ligands is attached through coordinate covalent bonds

chalcogen

element in group 16

chelate

complex formed from a polydentate ligand attached to a central metal

chelating ligand

ligand that attaches to a central metal ion by bonds from two or more donor atoms

chemical reduction

method of preparing a representative metal using a reducing agent

chemistry

study of the composition, properties, and interactions of matter

chlor-alkali process

electrolysis process for the synthesis of chlorine and sodium hydroxide

cis configuration

configuration of a geometrical isomer in which two similar groups are on the same side of an imaginary reference line on the molecule

color-change interval

range in pH over which the color change of an indicator is observed

common ion effect

effect on equilibrium when a substance with an ion in common with the dissolved species is added to the solution; causes a decrease in the solubility of an ionic species, or a decrease in the ionization of a weak acid or base

complex ion

ion consisting of a central atom surrounding molecules or ions called ligands via coordinate covalent bonds

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

concentration cell

galvanic cell comprising half-cells of identical composition but for the concentration of one redox reactant or product

conjugate acid

substance formed when a base gains a proton

conjugate base

substance formed when an acid loses a proton

coordinate covalent bond

(also, dative bond) covalent bond in which both electrons originated from the same atom

coordination compound

stable compound in which the central metal atom or ion acts as a Lewis acid and accepts one or more pairs of electrons

coordination number

number of coordinate covalent bonds to the central metal atom in a complex or the number of closest contacts to an atom in a crystalline form

coordination sphere

central metal atom or ion plus the attached ligands of a complex

core electron

electron in an atom that occupies the orbitals of the inner shells

corrosion

degradation of metal via a natural electrochemical process

coupled equilibria

system characterized the simultaneous establishment of two or more equilibrium reactions sharing one or more reactant or product

covalent bond

attractive force between the nuclei of a molecule’s atoms and pairs of electrons between the atoms

one-half the distance between the nuclei of two identical atoms when they are joined by a covalent bond

crystal field splitting

difference in energy between the t2g and eg sets or t and e sets of orbitals

crystal field theory

model that explains the energies of the orbitals in transition metals in terms of electrostatic interactions with the ligands but does not include metal ligand bonding

d-block element

one of the elements coordination compound groups 3–11 with valence electrons in d orbitals

degenerate orbitals

orbitals that have the same energy

diamagnetism

phenomenon in which a material is not magnetic itself but is repelled by a magnetic field; it occurs when there are only paired electrons present

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

diprotic acid

acid containing two ionizable hydrogen atoms per molecule

diprotic base

base capable of accepting two protons

disproportionation reaction

chemical reaction where a single reactant is simultaneously reduced and oxidized; it is both the reducing agent and the oxidizing agent

dissociation constant (Kd)

equilibrium constant for the decomposition of a complex ion into its components

dissolved

describes the process by which solute components are dispersed in a solvent

donor atom

atom in a ligand with a lone pair of electrons that forms a coordinate covalent bond to a central metal

Downs cell

electrochemical cell used for the commercial preparation of metallic sodium (and chlorine) from molten sodium chloride

dry cell

primary battery, also called a zinc-carbon battery, based on the spontaneous oxidation of zinc by manganese(IV)

e_g orbitals

set of two d orbitals that are oriented on the Cartesian axes for coordination complexes; in octahedral complexes, they are higher in energy than the t2g orbitals

effective nuclear charge

charge that leads to the Coulomb force exerted by the nucleus on an electron, calculated as the nuclear charge minus shielding

electrode potential

the potential of a cell in which the half-cell of interest acts as a cathode when connected to the standard hydrogen electrode

electrolysis

process using electrical energy to cause a nonspontaneous process to occur

electrolytic cell

electrochemical cell in which an external source of electrical electrolysis power is used to drive an otherwise nonspontaneous process

electron affinity

energy change associated with addition of an electron to a gaseous atom or ion

electron configuration

listing that identifies the electron occupancy of an atom’s shells and subshells

electron-pair geometry

arrangement around a central atom of all regions of electron density (bonds, lone pairs, or unpaired electrons)

electronegativity

tendency of an atom to attract electrons in a bond to itself

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

equatorial position

one of the three positions in a trigonal bipyramidal geometry with 120° angles between them; the axial positions are located at a 90° angle

equilibrium

state of a reversible reaction in which the forward and reverse processes occur at equal rates

equilibrium constant (K)

value of the reaction quotient for a system at equilibrium; may be expressed using concentrations (Kc) or partial pressures (Kp)

f-block element

(also, inner transition element) one of the elements with atomic numbers 58–71 or 90–103 that have valence electrons in f orbitals; they are frequently shown offset below the periodic table

charge on 1 mol of electrons; F = 96,485 C/mol e−

first transition series

transition elements in the fourth period of the periodic table (first row of the d-block), atomic numbers 21–29

formation constant (Kf)

(also, stability constant) equilibrium constant for the formation of a complex ion from its components

fourth transition series

transition elements in the seventh period of the periodic table (fourth row of the d-block), atomic numbers 89 and 104–111

Frasch process

important in the mining of free sulfur from enormous underground deposits

fuel cell

devices similar to galvanic cells that require a continuous feed of redox reactants; also called a flow battery

galvanic (voltaic) cell

electrochemical cell in which a spontaneous redox reaction takes place; also called a voltaic cell

galvanization

method of protecting iron or similar metals from corrosion by coating with a thin layer of more easily oxidized zinc.

geometric isomers

isomers that differ in the way in which atoms are oriented in space relative to each other, leading to different physical and chemical properties

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

Haber process

main industrial process used to produce ammonia from nitrogen and hydrogen; involves the use of an iron catalyst and elevated temperatures and pressures

half cell

component of a cell that contains the redox conjugate pair (“couple”) of a single reactant

halide

compound containing an anion of a group 17 element in the 1− oxidation state (fluoride, F−; chloride, Cl−; bromide, Br−; and iodide, I−)

Hall–Héroult cell

electrolysis apparatus used to isolate pure aluminum metal from a solution of alumina in molten cryolite

halogen

element in group 17

Henderson-Hasselbalch equation

logarithmic version of the acid ionization constant expression, conveniently formatted for calculating the pH of buffer solutions

heterogeneous catalyst

catalyst present in a different phase from the reactants, furnishing a surface at which a reaction can occur

heterogeneous equilibria

equilibria in which reactants and products occupy two or more different phases

high-spin complex

complex in which the electrons maximize the total electron spin by singly populating all of the orbitals before pairing two electrons into the lower-energy orbitals

homogeneous catalyst

catalyst present in the same phase as the reactants

homogeneous equilibria

equilibria in which all reactants and products occupy the same phase

homonuclear diatomic molecule

molecule consisting of two identical atoms

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

hydrate

compound containing one or more water molecules bound within its crystals

hydrogen carbonate

salt of carbonic acid, H2CO3 (containing the anion HCO3-) in which one hydrogen atom has been replaced; an acid carbonate; also known as bicarbonate ion

hydrogen halide

binary compound formed between hydrogen and the halogens: HF, HCl, HBr, and HI

hydrogenation

addition of hydrogen (H2) to reduce a compound

hydrometallurgy

process in which a metal is separated from a mixture by first converting it into soluble ions, extracting the ions, and then reducing the ions to precipitate the pure metal

hydroxide

compound of a metal with the hydroxide ion OH− or the group −OH

hypothesis

tentative explanation of observations that acts as a guide for gathering and checking information

inert electrode

electrode that conducts electrons to and from the reactants in a half-cell but that is not itself oxidized or reduced

inert gas

(also, noble gas) element in group 18

inert pair effect

tendency of heavy atoms to form ions in which their valence s electrons are not lost

inner transition metal

(also, lanthanide or actinide) element in the bottom two rows; if in the first row, also called lanthanide, or if in the second row, also called actinide

interhalogen

compound formed from two or more different halogens

ion-product constant for water (Kw)

equilibrium constant for the autoionization of water

ionic bond

electrostatic forces of attraction between the oppositely charged ions of 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
isoelectronic

ionization isomer

(or coordination isomer) isomer in which an anionic ligand is replaced by the counter ion in the inner coordination sphere

isoelectronic

group of ions or atoms that have identical electron configurations

lanthanide

inner transition metal in the top of the bottom two rows of the periodic table

lanthanide series

(also, lanthanoid series) lanthanum and the elements in the first row or the f-block, atomic numbers 57–71

lattice energy

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 mass action

when a reversible reaction has attained equilibrium at a given temperature, the reaction quotient remains constant

Le Châtelier’s principle

an equilibrium subjected to stress will shift in a way to counter the stress and re-establish equilibrium

rechargeable battery commonly used in automobiles; it typically comprises six galvanic cells based on Pb half-reactions in acidic solution

leveling effect

observation that acid-base strength of solutes in a given solvent is limited to that of the solvent’s characteristic acid and base species (in water, hydronium and hydroxide ions, respectively)

Lewis acid

any species that can accept a pair of electrons and form a coordinate covalent bond

compound or ion that contains a coordinate covalent bond between a Lewis acid and a Lewis base

Lewis acid-base chemistry

reactions involving the formation of coordinate covalent bonds

Lewis base

any species that can donate a pair of electrons and form a coordinate covalent bond

ligand

ion or neutral molecule attached to the central metal ion in a coordination compound

linear

shape in which two outside groups are placed on opposite sides of a central atom

linear combination of atomic orbitals

technique for combining atomic orbitals to create molecular orbitals

coordination compound that possesses a ligand that can bind to the transition metal in two different ways (CN− vs. NC−)

lithium ion battery

widely used rechargeable battery commonly used in portable electronic devices, based on lithium ion transfer between the anode and cathode

low-spin complex

complex in which the electrons minimize the total electron spin by pairing in the lower-energy orbitals before populating the higher-energy orbitals

macroscopic domain

realm of everyday things that are large enough to sense directly by human sight and touch

main-group element

(also, representative element) element in groups 1, 2, and 13–18
metal element that is shiny, malleable, good conductor of heat and electricity

metal (representative)

atoms of the metallic elements of groups 1, 2, 12, 13, 14, 15, and 16, which form ionic compounds by losing electrons from their outer s or p orbitals

metalloid

element that conducts heat and electricity moderately well, and possesses some properties of metals and some properties of nonmetals
noble gas (also, inert gas) element in group 18

microscopic domain

realm of things that are much too small to be sensed directly

microstate

possible configuration or arrangement of matter and energy within a system

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

molecular compound

(also, covalent compound) composed of molecules formed by atoms of two or more different elements

molecular orbital

region of space in which an electron has a high probability of being found in a molecule

molecular orbital diagram

visual representation of the relative energy levels of molecular orbitals

molecular orbital theory

model that describes the behavior of electrons delocalized throughout a molecule in terms of the combination of atomic wave functions

molecular structure

structure that includes only the placement of the atoms in the molecule

monatomic ion

ion composed of a single atom

monodentate

ligand that attaches to a central metal through just one coordinate covalent bond

monoprotic acid

acid containing one ionizable hydrogen atom per molecule

Nernst equation

relating the potential of a redox system to its composition

neutral

describes a solution in which [H3O+] = [OH−]

rechargeable battery based on Ni/Cd half-cells with applications similar to those of lithium ion batteries

nitrogen fixation

formation of nitrogen compounds from molecular nitrogen

nomenclature

system of rules for naming objects of interest

nonmetal

element that appears dull, poor conductor of heat and electricity
period (also, series) horizontal row of the periodic table

nonspontaneous process

process that requires continual input of energy from an external source

octahedral

shape in which six outside groups are placed around a central atom such that a three-dimensional shape is generated with four groups forming a square and the other two forming the apex of two pyramids, one above and one below the square plane

optical isomer

(also, enantiomer) molecule that is a nonsuperimposable mirror image with identical chemical and physical properties, except when it reacts with other optical isomers

orbital diagram

pictorial representation of the electron configuration showing each orbital as a box and each electron as an arrow

Ostwald process

industrial process used to convert ammonia into nitric acid

oxide

binary compound of oxygen with another element or group, typically containing O2− ions or the group –O– or =O

oxyacid

compound that contains hydrogen, oxygen, and one other element, bonded in a way that imparts acidic properties to the compound (ability to release H+ ions when dissolved in water)

oxyanion

polyatomic anion composed of a central atom bonded to oxygen atoms

ozone

allotrope of oxygen; O3

pairing energy (P)

energy required to place two electrons with opposite spins into a single orbital

paramagnetism

phenomenon in which a material is not magnetic itself but is attracted to a magnetic field; it occurs when there are unpaired electrons present

passivation

metals with a protective nonreactive film of oxide or other compound that creates a barrier for chemical reactions; physical or chemical removal of the passivating film allows the metals to demonstrate their expected chemical reactivity

percent ionization

ratio of the concentration of ionized acid to initial acid concentration expressed as a percentage

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

peroxide

molecule containing two oxygen atoms bonded together or as the anion, $${\text{O}}_{2}{}^{2-}$$

pH

logarithmic measure of the concentration of hydronium ions in a solution

photosynthesis

process whereby light energy promotes the reaction of water and carbon dioxide to form carbohydrates and oxygen; this allows photosynthetic organisms to store energy

Pidgeon process

chemical reduction process used to produce magnesium through the thermal reaction of magnesium oxide with silicon

platinum metals

group of six transition metals consisting of ruthenium, osmium, rhodium, iridium, palladium, and platinum that tend to occur in the same minerals and demonstrate similar chemical properties

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

polar molecule

(also, dipole) molecule with an overall dipole moment

polyatomic ion

ion composed of more than one atom

polydentate ligand

ligand that is attached to a central metal ion by bonds from two or more donor atoms, named with prefixes specifying how many donors are present (e.g., hexadentate = six coordinate bonds formed)

polymorph

variation in crystalline structure that results in different physical properties for the resulting compound

polymorph silicate

compound containing silicon-oxygen bonds, with silicate tetrahedra connected in rings, sheets, or three-dimensional networks, depending on the other elements involved in the formation of the compounds

primary cell

nonrechargeable battery, suitable for single use only

pure covalent bond

(also, nonpolar covalent bond) covalent bond between atoms of identical electronegativities

rare earth element

collection of 17 elements including the lanthanides, scandium, and yttrium that often occur together and have similar chemical properties, making separation difficult

reaction quotient (Q)

mathematical function describing the relative amounts of reactants and products in a reaction mixture; may be expressed in terms of concentrations (Qc) or pressures (Qp)

representative element

(also, main-group element) element in columns 1, 2, and 12–18 series (also, period) horizontal row of the period table

representative metal

metal among the representative elements

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

reversible reaction

chemical reaction that can proceed in both the forward and reverse directions under given conditions

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.

sacrificial anode

electrode constructed from an easily oxidized metal, often magnesium or zinc, used to prevent corrosion of metal objects via cathodic protection

salt bridge

tube filled with inert electrolyte solution

scientific method

path of discovery that leads from question and observation to law or hypothesis to theory, combined with experimental verification of the hypothesis and any necessary modification of the theory

second law of thermodynamics

all spontaneous processes involve an increase in the entropy of the universe

second transition series

transition elements in the fifth period of the periodic table (second row of the d-block), atomic numbers 39–47

secondary cell

battery designed to allow recharging

selective precipitation

process in which ions are separated using differences in their solubility with a given precipitating reagent

silicate

compound containing silicon-oxygen bonds, with silicate tetrahedra connected in rings, sheets, or three-dimensional networks, depending on the other elements involved in the formation of the compounds

smelting

process of extracting a pure metal from a molten ore

solubility product constant (Ksp)

equilibrium constant for the dissolution of an ionic compound

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

spectrochemical series

ranking of ligands according to the magnitude of the crystal field splitting they induce

spontaneous change

process that takes place without a continuous input of energy from an external source

standard cell potential

the cell potential when all reactants and products are in their standard states (1 bar or 1 atm or gases; 1 M for solutes), usually at 298.15 K

standard electrode potential

electrode potential measured under standard conditions (1 bar or 1 atm for gases; 1 M for solutes) usually at 298.15 K

standard entropy (S°)

entropy for one mole of a substance at 1 bar pressure; tabulated values are usually determined at 298.15 K

standard entropy change (Delta S°)

change in entropy for a reaction calculated using the standard entropies

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 (Gf)

change in free energy accompanying the formation of one mole of substance from its elements in their standard states

standard hydrogen electrode (SHE)

half-cell based on hydrogen ion production, assigned a potential of exactly 0 V under standard state conditions, used as the universal reference for measuring electrode potential

steel

material made from iron by removing impurities in the iron and adding substances that produce alloys with properties suitable for specific uses

stepwise ionization

process in which a polyprotic acid is ionized by losing protons sequentially

strong-field ligand

ligand that causes larger crystal field splittings

superconductor

material that conducts electricity with no resistance

symbolic domain

specialized language used to represent components of the macroscopic and microscopic domains, such as chemical symbols, chemical formulas, chemical equations, graphs, drawings, and calculations

T_2g orbitals

set of three d orbitals aligned between the Cartesian axes for coordination complexes; in octahedral complexes, they are lowered in energy compared to the eg orbitals according to CFT

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

third law of thermodynamics

entropy of a perfect crystal at absolute zero (0 K) is zero

third transition series

transition elements in the sixth period of the periodic table (third row of the d-block), atomic numbers 57 and 72–79

titration curve

plot of some sample property (such as pH) versus volume of added titrant

trans configuration

configuration of a geometrical isomer in which two similar groups are on opposite sides of an imaginary reference line on the molecule

transition metal

element in groups 3–12 (more strictly defined, 3–11; see chapter on transition metals and coordination chemistry)

trigonal bipyramidal

shape in which five outside groups are placed around a central atom such that three form a flat triangle with 120° angles between each pair and the central atom, and the other two form the apex of two pyramids, one above and one below the triangular plane

trigonal planar

shape in which three outside groups are placed in a flat triangle around a central atom with 120° angles between each pair and the central atom

triprotic acid

acid that contains three ionizable hydrogen atoms per molecule

valence electrons

electrons in the outermost or valence shell (highest value of n) of a ground-state atom

valence shell

outermost shell of electrons in a ground-state atom

valence shell electron-pair repulsion theory (VSEPR)

theory used to predict the bond angles in a molecule based on positioning regions of high electron density as far apart as possible to minimize electrostatic repulsion

vector

quantity having magnitude and direction

weak-field ligand

ligand that causes small crystal field splittings