Glossary
- Page ID
- 279429
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)| Words (or words that have the same definition) | The definition is case sensitive | (Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages] | (Optional) Caption for Image | (Optional) External or Internal Link | (Optional) Source for Definition |
|---|---|---|---|---|---|
| (Eg. "Genetic, Hereditary, DNA ...") | (Eg. "Relating to genes or heredity") |  |
The infamous double helix | CC-BY-SA; Delmar Larsen |
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Word(s) |
Definition |
Image | Caption | Link | Source |
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| Sample Word 1 | Sample Definition 1 | ||||
| acid | Compound that increases the concentration of H+ ions in solution | ||||
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abbreviated electron configuration |
An electron configuration that uses one of the noble gases to represent the core of electrons up to that element. |
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absolute zero |
The minimum possible temperature, labeled 0 K (zero kelvins) |
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acid |
A compound that increases the amount of H+ ions in an aqueous solution |
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acid dissociation constant (Ka) |
The equilibrium constant for the dissociation of a weak acid into ions |
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acid salt |
An ionic compound whose aqueous solution is slightly acidic |
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activated complex |
See transition state |
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activation energy (Ea) |
The minimum amount of kinetic energy molecules must possess for an effective collision to occur |
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active site |
Area of enzymatic action where substrate molecules react |
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activity series |
A list of elements that will replace elements below them in single-replacement reactions |
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actual yield |
The amount that is actually produced in a chemical reaction |
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addition reaction |
A reaction where atoms are added across a double or triple bond |
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adhesion |
The tendency of a substance to interact with other substances because of intermolecular forces |
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adsorb |
Bind to the surface of another substance |
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alcohol |
An organic compound that contains an OH functional group |
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aldehyde |
A compound that has a carbonyl functional group at the end of a chain of C atoms |
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aliphatic hydrocarbons |
A hydrocarbon based on chains of C atoms |
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alkaline battery |
A type of dry cell that contains an alkaline (i.e., basic) moist paste, rather than an acidic paste |
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alkane |
An aliphatic hydrocarbon with only single covalent bonds |
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alkene |
An aliphatic hydrocarbon that contains a C–C double bond |
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alkyl halide |
An organic compound that contains a halogen atom |
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alkyne |
An aliphatic hydrocarbon that contains a C–C triple bond |
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alpha particle |
A type of radioactive emission equivalent to a helium nucleus |
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amide group |
A functional group that is the combination of the amine and carbonyl functional groups |
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amide bond |
The bond between the N atom and the C atom in an amide. |
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amine |
An organic derivative of ammonia |
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amorphous solid |
A solid with no long-term structure or repetition |
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amphiprotic |
A substance that can act as a proton donor or a proton acceptor |
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analyte |
The reagent of unknown concentration |
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angular momentum quantum number (ℓ) |
An index that affects the energy and the spatial distribution of an electron in an atom. |
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anion |
A species with an overall negative charge |
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anode |
The half cell that contains the oxidation reaction |
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antibonding molecular orbital |
A higher energy molecular orbital generated by destructive combination of atomic orbitals |
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aromatic hydrocarbons |
Flat ring systems, which contain continuously overlapping p orbitals, such as benzene |
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Arrhenius acid |
A compound that increases the hydrogen ion concentration in aqueous solution |
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Arrhenius base |
A compound that increases the hydroxide ion concentration in aqueous solution |
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atmosphere (atm) |
A unit of pressure equal to the average atmospheric pressure at sea level; defined as exactly 760 mmHg |
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atom |
The smallest piece of an element that maintains the identity of that element |
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atomic mass |
The sum of the number of protons and neutrons in a nucleus |
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atomic mass |
The weighted average of the masses of the isotopes that compose an element |
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atomic mass unit |
One-twelfth of the mass of a carbon-12 atom |
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atomic number |
The number of protons in an atom |
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atomic radius |
An indication of the size of an atom. |
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atomic symbol |
A one- or two-letter representation of the name of an element |
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atomic theory |
The concept that atoms play a fundamental role in chemistry |
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aufbau principle |
The way that electrons fill the lowest energy orbitals first. From the German for “building up.” |
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autoionization constant of water (Kw) |
The product of the hydrogen ion and hydroxide ion concentrations |
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autoionization of water |
Water molecules act as acids (proton donors) and bases (proton acceptors) with each other to a tiny extent in all aqueous solutions |
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Avogadro’s law |
A gas law that relates number of particles to volume |
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balanced chemical equation |
A condition when the reactants and products of a chemical equation have the same number of atoms of all elements present |
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base |
A compound that increases the amount of OH− ions in an aqueous solution |
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basic salt |
An ionic compound whose aqueous solution is slightly basic |
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becquerel (Bq) |
A unit of radioactivity equal to 1 decay per second |
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beta particle |
A type of radioactive emission equivalent to an electron |
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boiling (or vaporization) |
The process of a liquid becoming a gas |
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boiling point |
The characteristic temperature at which a liquid becomes a gas |
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boiling point elevation |
The increase of a solution’s boiling point because of the presence of solute |
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boiling point elevation constant (Kb) |
The constant that relates the molality concentration of a solution and its boiling point change |
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bond energy |
The approximate amount of energy needed to break a covalent bond |
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bond order |
A method of evaluating bond strength |
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bonding electron pair |
A pair of electrons that makes a covalent bond |
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bonding molecular orbital |
The lower energy molecular orbital generated by constructive combination of atomic orbitals |
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Boyle’s law |
A gas law that relates pressure and volume at constant temperature and amount |
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branched hydrocarbons |
A carbon compound that is not a straight chain, having substituents appended to the longest chain |
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Brønsted-Lowry acid |
Any species that can donate a proton to another molecule |
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Brønsted-Lowry base |
Any species that can accept a proton from another molecule |
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buffer |
A solution that resists dramatic changes in pH |
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buffer capacity |
The amount of strong acid or base a buffer can counteract |
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burette or buret |
A precisely calibrated volumetric delivery tube |
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calorie |
A unit of energy measurement originally defined in terms of warming up a given quantity of water. 1 cal = 4.184 J |
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calorimeter |
A container used to measure the heat of a chemical reaction. |
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calorimetry |
The process of measuring enthalpy changes in chemical reactions. |
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capillary action |
The behavior of a liquid in narrow surfaces due to differences in adhesion and cohesion |
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carbonyl group |
A functional group where an O atom and a C atom are joined with a double bond |
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carboxyl group |
A functional group composed of a carbonyl group and an OH group |
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carboxylate ion |
A negatively charged ion derived from a carboxylic acid |
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carboxylic acid |
A molecule with a carboxyl group |
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catalyst |
A substance that increases the speed of a reaction |
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catalyst |
A substance thaty accelerates a reaction by participating in it without being consumed |
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catalyst |
A substance that lowers the activation energy of a specific reaction by providing an alternate reaction pathway |
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cathode |
The half cell that contains the reduction reaction |
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cation |
A species with an overall positive charge |
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central atom |
The atom in the center of a molecule |
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Charles’s law |
A gas law that relates volume and temperature at constant pressure and amount |
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chemical bond |
The connection between two atoms in a molecule |
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chemical change |
The process of demonstrating a chemical property |
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chemical equation |
A concise way of representing a chemical reaction |
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chemical equilibrium |
The point at which forward and reverse chemical reactions balance each other’s progress |
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chemical nomenclature |
A very specific system for naming compounds, in which unique substances get unique names |
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chemical property |
A characteristic that describes how matter changes form in the presence of other matter |
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chemistry |
The study of the interactions of matter with other matter and with energy |
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coefficient |
The part of a number in scientific notation that is multiplied by a power of 10 |
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coefficient |
A number in a chemical equation indicating more than one molecule of the substance |
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cohesion |
The tendency of a substance to interact with itself |
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colligative property |
A property of solutions related to the fraction that the solute particles occupy in the solution, not their identity |
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collision theory |
The theory that reactions occur when reactant molecules “effectively collide” |
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combined gas law |
A gas law that combines pressure, volume, and temperature |
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combustion reaction |
A chemical reaction in which a reactant combines with oxygen to produce oxides of all other elements as products |
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complete ionic equation |
A chemical equation in which the dissolved ionic compounds are written as separated ions |
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composition reaction |
A chemical reaction in which a single substance is produced from multiple reactants |
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compound |
A combination of more than one element |
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compressibility factor |
A measure of the extent of deviation from ideal gas behaviour. |
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concentrated solution |
A solution with a lot of solute |
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concentration |
How much solute is dissolved in a given amount of solvent |
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concentration (verb) |
The removal of solvent, which increases the concentration of the solute in the solution |
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condensation |
The process of a gas becoming a liquid |
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condensed structure |
A listing of the atoms bonded to each C atom in a chain |
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conjugate acid-base pair |
Two species whose formulas differ by only a hydrogen ion |
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continuous spectrum |
An image that contains all colours of light. |
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conversion factor |
A fraction that can be used to convert a quantity from one unit to another |
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covalent bond |
A chemical bond formed by two atoms sharing electrons. |
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covalent network solids |
A crystalline solid composed of atoms of one or more elements that are covalently bonded together in a seemingly never-ending fashion |
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critical point |
The point at the highest temperature and pressure at which liquids and gases remain distinguishable |
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crystalline solid |
A solid with a regular, repeating three-dimensional structure |
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curie |
A unit of radioactivity equal to 3.7×1010 decays/s |
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d block |
The columns of the periodic table in which d subshells are being occupied. |
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Dalton’s law of partial pressures |
The total pressure of a gas mixture, Ptot, is equal to the sum of the partial pressures of the components, Pi |
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daughter isotope |
The product left over from the parent isotope in a nuclear equation |
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decomposition reaction |
A chemical reaction in which a single substance becomes more than one substance |
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degrees |
The unit of temperature scales |
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density |
A physical property defined as a substance’s mass divided by its volume |
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deposition |
The process of a gas becoming a solid |
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derived unit |
A unit that is a product or a quotient of a fundamental unit |
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diatomic molecule |
A molecule with only two atoms |
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diffusion |
The movement of gas molecules through one or more additional types of gas via random molecular motion |
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dilute |
A solution with very little solute |
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dilution |
The addition of solvent, which decreases the concentration of the solute in the solution |
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dilution equation |
The mathematical formula for calculating new concentrations or volumes when a solution is diluted or concentrated |
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dipole-dipole interactions |
An intermolecular force caused by molecules with a permanent dipole |
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dispersion force (or London dispersion force) |
An intermolecular force caused by the instantaneous position of an electron in a molecule |
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dissociation |
The process of an ionic compound separating into ions when it dissolves |
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double bond |
A covalent bond composed of two pairs of bonding electrons |
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double-replacement reaction |
A chemical reaction in which parts of two ionic compounds are exchanged |
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dry cell |
A modern battery that does not contain large amounts of aqueous solution |
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dynamic equilibrium |
When a process still occurs but the opposite process also occurs at the same rate so that there is no net change in the system. |
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effective nuclear charge (Zeff) |
The net nuclear charge felt by valence electrons. |
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effusion |
The movement of gas molecules from one container to another via a tiny hole |
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electrodes |
The cathode or anode of a voltaic cell |
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electrolysis |
The process of making a nonspontaneous redox reaction occur by forcing electricity into a cell |
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electrolytic cell |
A cell into which electricity is forced to make a nonspontaneous reaction occur |
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electromagnetic spectrum |
The full span of the possible wavelengths, frequencies, and energies of light. |
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electron |
A tiny subatomic particle with a negative charge |
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electron affinity (EA) |
The energy change when a gas-phase atom accepts an electron. |
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electron configuration |
A listing of the shell and subshell labels. |
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electron deficient molecules |
A molecule with less than eight electrons in the valence shell of an atom |
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electron group geometry |
how electron groups (bonds and nonbonding electron pairs) are arranged |
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electron groups |
A covalent bond of any type or a lone electron pair |
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electron shell |
A term used to describe electrons with the same principal quantum number. |
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electronegativity |
A scale for judging how much atoms of any element attract electrons |
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electroplating |
The deposition of a thin layer of metal on an object for protective or decorative purposes |
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element |
A substance that cannot be broken down into simpler chemical substances by ordinary chemical means |
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elementary step |
Each event that occurs in a chemical reaction as a result of an effective collision |
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elimination reaction |
The removal of a functional group (either X or OH) and a H atom from an adjacent carbon |
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endothermic |
A chemical reaction that has a positive change in enthalpy. |
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energy |
The ability to do work. |
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enthalpy change |
The heat of a process at constant pressure. Denoted as ΔH. |
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enthalpy of formation |
The enthalpy change for a formation reaction; denoted as ΔHf. |
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enthalpy of fusion |
The amount of energy needed to change from a solid to a liquid or from a liquid to a solid |
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enthalpy of sublimation |
The amount of energy needed to change from a solid to a gas or from a gas to a solid |
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enthalpy of vaporization |
The amount of energy needed to change from a liquid to a gas or from a gas to a liquid |
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entropy |
The level of randomness (or disorder) of a system, or a measure of the energy dispersal of the molecules in the system |
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enzyme |
Protein molecules which serve to catalyze biochemical reactions |
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enzyme-substrate complex |
The binding of substrate to the enzymatic active site |
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equilibrium constant (Keq) |
A numerical value that relates to the ratio of products and reactants at equilibrium |
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equivalence point |
The point of the reaction when all the analyte has been reacted with the titrant |
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ester group |
A functional group made by combining a carboxylic acid with an alcohol |
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ether group |
A functional group that has an O atom attached to two organic groups |
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evaporation |
The formation of a gas phase from a liquid at temperatures below the boiling point |
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exact number |
A number from a defined relationship that technically has an infinite number of significant figures |
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exothermic |
A chemical reaction that has a negative change in enthalpy. |
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expanded valence shell molecules |
A molecule with more than eight electrons in the valence shell of an atom |
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experiment |
A test of the natural universe to see if a guess (hypothesis) is correct |
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exponent |
The raised number to the right of a 10 indicating the number of factors of 10 in the original number |
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f block |
The columns of the periodic table in which f subshells are being occupied. |
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fission |
The breaking apart of an atomic nucleus into smaller nuclei |
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formation reaction |
A chemical reaction that forms one mole of a substance from its constituent elements in their standard states. |
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freezing point depression |
The decrease of a solution’s freezing point because of the presence of solute |
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freezing point depression constant (Kf) |
The constant that relates the molality concentration of a solution and its freezing point change |
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frequency |
The number of cycles of light that pass a given point in one second. |
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frequency factor (A) |
A factor that takes into account the frequency of reactions and the likelihood of correct molecular orientation |
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frontier molecular orbitals |
A term which refers to the HOMO and LUMO, the most likely orbitals to be involved in chemical reactions or processes |
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functional group |
A collection of atoms or bonds with certain characteristic reactions |
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fundamental units |
One of the seven basic units of SI used in science |
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gamma ray |
A type of radioactive emission that is a very energetic form of electromagnetic radiation |
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gas law |
A simple mathematical formula that allows one to model, or predict, the behaviour of a gas |
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Gay-Lussac’s law |
A gas law that relates pressure with absolute temperature |
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Geiger counter |
An electrical device that detects radioactivity |
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Gibbs free energy (G) |
A measure of spontaneity which incorporates both enthalpy and entropy |
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Graham’s law of effusion |
A law that relates the rate of effusion of a gas to the inverse of the square root of its molar mass. |
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gray (Gy) |
A unit of radioactive exposure equal to 100 rad |
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half cell |
A part of a voltaic cell that contains one half reaction |
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half reaction |
The individual oxidation or reduction reaction of a redox reaction |
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half reaction method |
The method of balancing redox reactions by writing and balancing the individual half reactions |
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half-life |
The amount of time it takes for one-half of a radioactive isotope to decay |
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half-life |
The amount of time required for the concentration of a reactant to drop to one half of its initial concentration |
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heat |
The transfer of energy from one body to another due to a difference in temperature. |
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heating curve |
A plot of the temperature versus the amount of heat added |
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Hess’s law |
When chemical equations are combined algebraically, their enthalpies can be combined in exactly the same way. |
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heterogeneous catalyst |
A catalyst that is in a different phase from one or more of the reactants |
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heterogeneous equilibrium |
An equilibrium in which more than one phase of reactants or products is present |
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heterogeneous mixture |
A non-uniform combination of more than one substance |
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HOMO |
The highest occupied molecular orbital |
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homogeneous catalyst |
A catalyst that is present in the same phase as the reactant molecules |
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homogeneous mixture |
A uniform mixture of more than one substance that behaves as a single substance |
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Hund’s rule |
One electron is placed in each degenerate orbital before pairing electrons in the same orbital. |
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hybridization |
A mathematical mixing of atomic orbitals |
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hydrocarbons |
An organic compound composed of carbon and hydrogen |
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hydrogen bonding |
The very strong interaction between molecules due to H atoms being bonded to N, O, or F atoms |
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hydrogenation reaction |
The reaction of hydrogen across a C–C double or triple bond, usually in the presence of a catalyst |
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hydronium ion |
The actual chemical species that represents a hydrogen ion in aqueous solution |
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hypothesis |
An educated guess about how the natural universe works |
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hyrolysis |
A reaction with water |
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ICE chart |
A table used to calculate equilibria values featuring rows of initial, change and equlibria concentration |
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ideal gas |
A gas that conforms exactly to the tenets of the kinetic molecular theory. |
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ideal gas law |
A gas law that relates all four independent physical properties of a gas under any conditions |
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indicator |
A substance whose color change indicates the equivalence point of a titration |
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initial rate |
The instantaneous rate at the start of a reaction |
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initial rates method |
A method to determine the rate law from the instantaneous reaction rate upon mixing the reactants |
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instantaneous reaction rate |
The rate of reaction at one instant in time |
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|
intermediate |
A chemical species does not appear in the overall balanced equation and is generated in one elementary step but used up in a subsequent step |
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|
ion |
A species with an overall electric charge |
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|
ionic compound |
A compound formed from positive and negative ions |
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|
ionic formula |
The chemical formula for an ionic compound |
||||
|
ionic solid |
A crystalline solid composed of ions |
||||
|
ionization energy (IE) |
The amount of energy required to remove an electron from an atom in the gas phase. |
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|
isolated system |
A system that does not allow a transfer of energy or matter into or out of itself. |
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|
isomer |
A molecule with the same molecular formula as another molecule but a different structure |
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|
isothermal |
A process that does not change the temperature |
||||
|
isotopes |
Atoms of the same element that have different numbers of neutrons |
||||
|
joule |
The SI unit of energy. |
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|
kelvin |
The fundamental unit of temperature in SI |
||||
|
ketone |
A compound where the carbonyl carbon is attached to two carbon chains |
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|
kinetic energy |
Energy due to motion |
||||
|
kinetic molecular theory of gases |
A model that helps us understand gases at the molecular level and their physical properties |
||||
|
kinetics |
The study of reaction rate and the factors that can influence reaction rate |
||||
|
law of conservation of energy |
Law of physics that states that the total energy of an isolated system does not increase or decrease. |
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|
law of mass action |
The relationship of the amounts of reactants and products at equilibrium |
||||
|
Le Chatelier’s principle |
If an equilibrium is stressed, then the reaction shifts to reduce the stress |
||||
|
Lewis diagram |
A representation of the valence electrons of an atom that uses dots around the symbol of the element. |
||||
|
limiting reagent |
The reactant that runs out first for a given chemical reaction |
||||
|
line spectrum |
An image that contains only certain colors of light |
||||
|
locant |
The numerical position of a substituent |
||||
|
lock and key model |
A simple model used to describe enzyme activity, where substrates must fit into appropriately shaped active sites |
||||
|
lone electron pairs |
A pair of electrons that does not make a covalent bond |
||||
|
LUMO |
The lowest unoccupied molecular orbital |
||||
|
magnetic quantum number (mℓ) |
The index that determines the orientation of the electron’s spatial distribution. |
||||
|
mass-mass calculation |
A calculation in which you start with a given mass of a substance and calculate the mass of another substance involved in the chemical equation |
||||
|
matter |
Anything that has mass and takes up space. |
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|
mean free path |
The average distance travelled by a molecule between collisions. |
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|
melting |
The process of a solid becoming a liquid |
||||
|
melting point |
The characteristic temperature at which a solid becomes a liquid |
||||
|
meniscus |
The curved surface a liquid makes as it approaches a solid barrier |
||||
|
metal |
An element that conducts electricity and heat well and is shiny, silvery, solid, ductile, and malleable |
||||
|
metallic solid |
A solid with the characteristic properties of a metal |
||||
|
microstate (W) |
A term used to describe different possible arrangements of molecular position and kinetic energy, at a particular thermodynamic state |
||||
|
millimeters of mercury (mmHg) |
The amount of pressure exerted by a column of mercury exactly 1 mm high |
||||
|
mixture |
A physical combination of more than one substance |
||||
|
molality (m) |
The number of moles of solute per kilogram of solvent |
||||
|
molar mass |
The mass of 1 mol of a substance in grams |
||||
|
molar volume |
The volume of exactly 1 mol of a gas; equal to 22.4 L at STP. |
||||
|
molarity (M) |
The number of moles of solute divided by the number of liters of solution |
||||
|
mole |
The number of things equal to the number of atoms in exactly 12 g of carbon-12; equals 6.022×1023 things |
||||
|
mole fraction |
The ratio of the number of moles of a component in a mixture divided by the total number of moles in the sample |
||||
|
mole fraction |
The ratio of the number of moles of a component to the total number of moles in a system |
||||
|
molecular formula |
A formal listing of what and how many atoms are in a molecule |
||||
|
molecular geometry |
how the atoms in a molecule are arranged |
||||
|
molecular mass |
The sum of the masses of the atoms in a molecule |
||||
|
molecular orbital theory (MO theory) |
A more sophisticated model of chemical bonding where new molecular orbitals are generated using a mathematical process called Linear Combination of Atomic Orbitals (LCAO) |
||||
|
molecular polarity |
The vector sum of the individual bond dipoles |
||||
|
molecular solid |
A crystalline solid whose components are covalently bonded molecules |
||||
|
molecularity |
The total number of molecules that participate in the effective collision of the elementary step |
||||
|
molecule |
The smallest part of a substance that has the physical and chemical properties of that substance |
||||
|
mole-mass calculation |
A calculation in which you start with a given number of moles of a substance and calculate the mass of another substance involved in the chemical equation, or vice versa |
||||
|
mole-mole calculation |
A stoichiometry calculation when one starts with moles of one substance and convert to moles of another substance using the balanced chemical equation |
||||
|
monomer |
The repeated unit of a polymer |
||||
|
net ionic equation |
A chemical equation with the spectator ions removed |
||||
|
neutral salt |
An ionic compound that does not affect the acidity of its aqueous solution |
||||
|
neutralization reaction |
The reaction of an acid with a base to produce water and a salt |
||||
|
neutron |
A subatomic particle with no charge |
||||
|
node (nodal plane) |
An area of zero electron density |
||||
|
nomenclature |
The rules of naming in organic chemistry |
||||
|
nonmetal |
An element that exists in various colors and phases, is brittle, and does not conduct electricity or heat well |
||||
|
nonpolar covalent bond |
The equal sharing of electrons in a covalent bond |
||||
|
normal boiling point |
The characteristic temperature at which a liquid becomes a gas when the surrounding pressure is exactly 1 atm |
||||
|
nuclear energy |
The controlled harvesting of energy from fission reactions |
||||
|
nuclear equation |
A chemical equation that emphasizes changes in atomic nuclei |
||||
|
nuclear model |
The model of an atom that has the protons and neutrons in a central nucleus with the electrons in orbit about the nucleus |
||||
|
nucleus |
The centre of an atom that contains protons and neutrons |
||||
|
odd-electron molecules |
A molecule with an odd number of electrons in the valence shell of an atom |
||||
|
orbital |
The specific set of principal, angular momentum, and magnetic quantum numbers for an electron. |
||||
|
osmosis |
The tendency of solvent molecules to pass through a semipermeable membrane due to concentration differences |
||||
|
osmotic pressure |
The tendency of a solution to pass solvent through a semipermeable membrane due to concentration differences |
||||
|
oxidation |
The loss of one or more electrons by an atom; an increase in oxidation number |
||||
|
oxidation number |
A number assigned to an atom that helps keep track of the number of electrons on the atom |
||||
|
oxidation-reduction (redox) reactions |
A chemical reaction that involves the transfer of electrons |
||||
|
p block |
The columns of the periodic table in which p subshells are being occupied. |
||||
|
parent isotope |
The reactant in a nuclear equation |
||||
|
parts per billion (ppb) |
Ratio of mass of solute to total mass of sample times 1,000,000,000 |
||||
|
parts per million (ppm) |
Ratio of mass of solute to total mass of sample times 1,000,000 |
||||
|
parts per thousand (ppth) |
Ratio of mass of solute to total mass of sample times 1,000 |
||||
|
Pauli exclusion principle |
No two electrons in an atom can have the same set of four quantum numbers. |
||||
|
percent yield |
Actual yield divided by theoretical yield times 100% to give a percentage between 0% and 100% |
||||
|
percentage composition by mass (or mass percentage, % m/m) |
Ratio of mass of solute to the total mass of a sample times 100 |
||||
|
periodic table |
A chart of all the elements |
||||
|
periodic trends |
The variation of properties versus position on the periodic table. |
||||
|
pH |
The negative logarithm of the hydrogen ion concentration |
||||
|
pH scale |
The range of values from 0 to 14 that describes the acidity or basicity of a solution |
||||
|
phase |
An important physical property that defines whether matter is a solid, liquid, gas or supercritical fluid |
||||
|
phase diagram |
A graphical representation of the equilibrium relationships that exist between the phases of a substance under specified pressures and temperatures |
||||
|
photon |
The name of a discrete unit of light acting as a particle. |
||||
|
physical change |
A change that occurs when a sample of matter changes one or more of its physical properties |
||||
|
physical property |
A characteristic that describes matter as it exists |
||||
|
pi bond (π bond) |
The sideways overlap of p orbitals, placing electron density on opposite sides of the inter-nuclear axis – a double or triple bond |
||||
|
Planck’s constant |
The proportionality constant between the frequency and the energy of light: 6.626 × 10 to the power of −34 J·s. |
||||
|
pOH |
The negative logarithm of the hydroxide ion concentration |
||||
|
polar covalent bond |
A covalent bond between different atoms that attract the shared electrons by different amounts and cause an imbalance of electron distribution |
||||
|
polarity |
A measure of the unequal sharing of electrons which has resulted in a dipole moment |
||||
|
polyatomic ions |
An ion that contains more than one atom |
||||
|
polymer |
A long molecule made of many repeating units |
||||
|
polymerization |
The process of making a polymer |
||||
|
polyprotic acid |
An acid capable of donating more than one H+ ion |
||||
|
precipitate |
A solid that falls out of solution in a precipitation reaction |
||||
|
precipitation reaction |
A chemical reaction in which two ionic compounds are dissolved in water and form a new ionic compound that does not dissolve |
||||
|
prefix |
A prefix used with a unit that refers to a multiple or fraction of a fundamental unit to make a more conveniently sized unit for a specific quantity |
||||
|
pressure |
Force per unit area |
||||
|
primary battery |
A battery that cannot be recharged |
||||
|
principal quantum number (n) |
The index that largely determines the energy of an electron in an atom. |
||||
|
product |
A final substance in a chemical equation |
||||
|
proton |
A subatomic particle with a positive charge |
||||
|
qualitative |
A description of the quality of an object |
||||
|
quantitative |
A description of a specific amount of something |
||||
|
quantization |
When a quantity is restricted to having only certain values. |
||||
|
quantum mechanics |
The theory of electrons that treats them as a wave. |
||||
|
quantum number |
An index that corresponds to a property of an electron, like its energy. |
||||
|
rad |
A unit of radioactive exposure equal to 0.01 J/g of tissue |
||||
|
radioactive decay |
The spontaneous change of a nucleus from one element to another |
||||
|
radioactivity |
Emanations of particles and radiation from atomic nuclei |
||||
|
Raoult’s law |
The mathematical formula for calculating the vapor pressure of a solution |
||||
|
rate constant (k) |
A proportionality constant specific to each reaction at a particular temperature |
||||
|
rate-determining step |
The slowest step in a multistep mechanism |
||||
|
rate law |
A mathematical relationship between the reaction rate and the reactant concentrations |
||||
|
reactant |
An initial substance in a chemical equation |
||||
|
reaction mechanism |
The bond making and bond breaking steps which occur at the molecular level during a chemical reaction |
||||
|
reaction order |
The sum of the concentration term exponents in a rate law equation |
||||
|
reaction rate |
The speed of a chemical reaction |
||||
|
real gas |
A gas that deviates from ideal behaviour. |
||||
|
redox reaction |
A chemical reaction that involves the transfer of electrons |
||||
|
reduction |
The gain of one or more electrons by an atom; a decrease in oxidation number |
||||
|
rem |
A unit of radioactive exposure that includes a factor to account for the type of radioactivity |
||||
|
ribozyme |
Ribonucleic acid (RNA) molecules capable of catalyzing certain chemical reactions |
||||
|
root-mean-square (rms) speed (urms) |
The speed of molecules having exactly the same kinetic energy as the average kinetic energy of the sample |
||||
|
s block |
The columns of the periodic table in which s subshells are being occupied |
||||
|
salt |
Any ionic compound that is formed from a reaction between an acid and a base |
||||
|
salt |
Any ionic compound that is formed from a reaction between an acid and a base |
||||
|
salt bridge |
A part of a voltaic cell that contains a solution of some ionic compound whose ions migrate to either side of the voltaic cell to maintain the charge balance |
||||
|
saturated hydrocarbons |
A carbon compound with the maximum possible number of H atoms in its formula |
||||
|
saturated solution |
A solution with the maximum amount of solute dissolved in it |
||||
|
science |
The process of knowing about the natural universe through observation and experiment |
||||
|
scientific law |
A specific statement that is thought to be never violated by the entire natural universe |
||||
|
scientific notation |
An expression of a number using powers of 10 |
||||
|
screening |
The repelling valence electrons by core electrons |
||||
|
second law of thermodynamics |
A spontaneous process will increase the entropy of the universe |
||||
|
secondary battery |
A battery that can be recharged |
||||
|
semimetal |
An element that has properties of both metals and nonmetals |
||||
|
semipermeable membrane |
A thin membrane that will pass certain small molecules but not others |
||||
|
SI unit |
International System of Units used by all scientists, literally translated from “le Système International d’unités.” |
||||
|
Sievert (Sv) |
Sievert (Sv) is a related unit and is defined as 100 rem |
||||
|
sigma bond (σ bond) |
Orbital overlap to form a bond which has cylindrical symmetry – a single bond |
||||
|
significant figures |
The limit of the number of places a measurement can be properly expressed with |
||||
|
silicones |
A polymer based on a silicon and oxygen backbone |
||||
|
single bond |
A covalent bond composed of one pair of electrons |
||||
|
single-replacement reaction |
A chemical reaction in which one element is substituted for another element in a compound |
||||
|
solidification |
The process of a liquid becoming a solid |
||||
|
solubility |
The maximum amount of a solute that can be dissolved in a given amount of a solvent |
||||
|
solubility rules |
General statements that predict which ionic compounds dissolve and which do not |
||||
|
solute |
The minor component of a solution |
||||
|
solution |
See homogeneous mixture |
||||
|
solvent |
The major component of a solution. |
||||
|
specific heat capacity |
The proportionality constant between heat, mass, and temperature change; also called specific heat. |
||||
|
spectator ion |
An ion that does nothing in the overall course of a chemical reaction |
||||
|
spin quantum number (m_s) |
The index that indicates one of two spin states for an electron. |
||||
|
spontaneous process |
A process that occurs without the influence of external forces or a change that moves a system towards equilibrium |
||||
|
standard molar entropy (So) |
The entropy of 1 mole of a substance in its standard state, at 1 atm of pressure |
||||
|
standard notation |
A straightforward expression of a number |
||||
|
standard temperature and pressure (STP) |
A set of benchmark conditions used to compare other properties of gases: 100 kPa for pressure and 273 K for temperature |
||||
|
stoichiometry |
The relating of one chemical substance to another using a balanced chemical reaction |
||||
|
strong acid |
Any acid that is 100% dissociated into ions in aqueous solution |
||||
|
strong base |
Any base that is 100% dissociated into ions in aqueous solution |
||||
|
sublimation |
The process of a solid becoming a gas |
||||
|
subshell |
A term used to describe electrons in a shell that have the same angular momentum quantum number. |
||||
|
substance |
Matter that has the same physical and chemical properties throughout. |
||||
|
substituent |
A branch off a main chain in a hydrocarbon |
||||
|
substrate |
The reactants which are specific for a biological catalyst |
||||
|
supercritical fluid |
A phase beyond the critical point, where liquid and gas phases are no longer distinct |
||||
|
supersaturated solution |
A unstable solution with more than the normal maximum amount of solute in it |
||||
|
surface tension |
An effect caused by an imbalance of forces on the atoms at the surface of a liquid |
||||
|
surrounding atoms |
An atom that makes covalent bonds to the central atom(s) |
||||
|
system |
The part of the universe that is under study. |
||||
|
temperature |
A measure of the average amount of kinetic energy a system contains |
||||
|
theoretical yield |
An amount that is theoretically produced as calculated using the balanced chemical reaction |
||||
|
theory |
A general statement that explains a large number of observations |
||||
|
thermochemical equation |
A chemical equation that includes an enthalpy change. |
||||
|
thiol |
The sulfur analog of an alcohol |
||||
|
third law of thermodynamics |
At absolute zero the entropy of a pure, perfect crystal is zero |
||||
|
titrant |
The reagent of known concentration |
||||
|
titration |
A chemical reaction performed quantitatively to determine the exact amount of a reagent |
||||
|
torr |
Another name for a millimeter of mercury |
||||
|
tracer |
A substance that can be used to follow the pathway of that substance through a structure |
||||
|
transition state |
The highest energy transitional point in the elementary step |
||||
|
triple bond |
A covalent bond composed of three pairs of bonding electrons |
||||
|
unsaturated hydrocarbons |
A carbon compound with less than the maximum possible number of H atoms in its formula |
||||
|
unsaturated solution |
A solution with less than the maximum amount of solute dissolved in it |
||||
|
valence electron |
An electron in the highest-numbered shell or in the last unfilled subshell. Valence electrons are those that are most likely to be involved in chemical reactions. |
||||
|
valence shell |
The highest-numbered shell in an atom that contains electrons. |
||||
|
valence shell electron pair repulsion theory (VSEPR) |
The general concept that estimates the shape of a simple molecule: electron pairs repel each other to get as far away from each other as possible |
||||
|
van der Waals equation |
An equation that compensates for deviations from ideal gas behaviour, correcting for intermolecular forces and the volume of gas molecules. |
||||
|
van’t Hoff factor (i) |
The number of particles each solute formula unit breaks apart into when it dissolves |
||||
|
vapor |
Material in the gas phase due to evaporation |
||||
|
vapor pressure |
The partial pressure exerted by evaporation of a liquid |
||||
|
vapor pressure depression |
The decrease of a solution’s vapor pressure because of the presence of a solute |
||||
|
vector quantity |
A quantity which has both a magnitude and direction |
||||
|
voltaic (galvanic) cell |
An apparatus that allows for useful electrical work to be extracted from a redox reaction. |
||||
|
wavelength |
The distance between corresponding points in two adjacent light cycles. |
||||
|
weak acid |
Any acid that is less than 100% dissociated into ions in aqueous solution |
||||
|
weak base |
Any base that is less than 100% dissociated into ions in aqueous solution |
||||
|
|
|
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