Many of the definitions below are the same as, or based on, corresponding definitions from other sources. Some definitions have been revised and either expanded or made more narrow to fit the scope of the course. Links to related Wikipedia articles are provided, if available, for your information.
Absorption. Absorption is a process in which atoms or molecules enter the bulk phase of a solid or liquid and are taken up within the volume of that phase. [Wikipedia]
Acid. A Brønsted-Lowry acid is a molecule or ion that can serve as a proton (H+) donor. [Wikipedia] A Lewis acid is a molecule or ion that has an empty orbital that is capable of accepting an electron pair from a Lewis base. [Wikipedia]
Acid Anhydride. An acid anhydride is a compound derived by dehydration of an acid. In inorganic chemistry, "anhydride" is an alternative name for some nonmetal oxides. For example, carbon dioxide, CO2, is sometimes called carbonic anhydride. [Wikipedia]
Acid Remainder. An acid remainder is the part of the molecule of an acid that includes all of its atoms but the hydrogen(s) that can be replaced with metal atoms. Now obsolete, the term "acid remainder" was broadly used before the acceptance of the Arrhenius theory of electrolytic dissociation by the chemical community.
Adsorbent. An adsorbent is a substance or mixture of substances that adsorbs other substances. [Wikipedia]
Adsorption. Adsorption is the process of attraction and adhesion of molecules, atoms or ions to a surface. [Wikipedia]
Alkane. An alkane is an acyclic hydrocarbon devoid of multiple carbon-carbon bonds with a general formula CnH2n+2. [Wikipedia]
Alkaline. A solution is alkaline if its pH is greater than 7. "Alkaline" is conventionally used as a synonym of "basic". [Wikipedia]
Alkene. An alkene, also known as olefin, is a hydrocarbons containing one carbon-carbon double bond, C=C. The general formula for alkenes is CnH2n. [Wikipedia]
Alkyl. An alkyl is a substituent with a general formula CnH2n+1, an alkane missing one hydrogen atom. [Wikipedia]
Alkyne. An alkyne is a hydrocarbons containing one carbon-carbon triple bond, C≡C. The general formula for alkynes is CnH2n-2. [Wikipedia]
Allotrope. An allotrope (also known as allotropic form or allotropic modification) is a simple substance that differs in structure from another simple substance formed by atoms of the same element. For example, ozone (O3) and oxygen (O2) are allotropes.
Allotropy. Allotropy, also known as allotropism, is the phenomenon of existence of two or more distinct simple substances formed by the same chemical element. [Wikipedia]
Alloy. An alloy is a mixture of two or more metals, conventionally made by co-melting and mixing the metals while they are liquids, followed by cooling. In a limited number of cases, a nonmetal can be a constituent of an alloy. For example, steel is an alloy of iron and carbon. Alloys can be homogeneous and heterogeneous. Homogeneous alloys are often called "solid solutions". [Wikipedia]
Alumina. Alumina is the common name for aluminum oxide, Al2O3. [Wikipedia]
Amalgam. An amalgam is an alloy of mercury (Hg) with one or more other metals. Depending on its composition, an amalgam may be a solid or a liquid. [Wikipedia]
Amorphous. An amorphous solid is a solid with no ordered structure that is characteristic of a crystalline solid. [Wikipedia]
Amphoterism. An amphoteric hydroxide is a hydroxide that can act as a base in the neutralization reaction with an acid and as an acid in the neutralization reaction with a base. Likewise, an amphoteric oxide is an oxide that can act as a basic oxide in the reaction with an acid and as an acidic oxide in the reaction with a base. [Wikipedia]
Anode. An anode is the positively charged electrode which attracts anions of an electrolyte and through which the electrons leave the electrolyte solution or melt. [Wikipedia]
Anti-caking Agent. An anti-caking agent is a substance added to powdered materials in order to prevent the formation of lumps on storage. [Wikipedia]
Aqua Regia. Aqua regia is a mixture of concentrated hydrochloric and nitric acids, optimally in a 3:1 molar ratio. The name aqua regia comes from Latin, meaning "royal water" or "king's water" because a mixture of HCl to HNO3 dissolves gold, the highly chemically inert "king of metals". Gold does not react with such strong acids as H2SO4, HCl alone or HNO3 alone. [Wikipedia]
Aqueous. An aqueous solution is a solution in water. The word "solution" is sometimes omitted in the name of an aqueous solution. For example, "aqueous NaOH" means an aqueous solution of NaOH. [Wikipedia]
Arene. An arene, or aromatic hydrocarbon, is a cyclic hydrocarbon with alternating double and single carbon-carbon bonds featuring delocalization of the π-electrons. [Wikipedia]
Asphyxiant. An asphyxiant gas is a nontoxic gas that, unlike oxygen, does not support breathing. Except for oxygen, all nontoxic gases are asphyxiants. [Wikipedia]
Atom. An atom is an electroneutral particle composed of negatively charged electrons surrounding a nucleus consisting of positively charged protons and uncharged neutrons. Molecules are made up of atoms. [Wikipedia]
Atomic Mass Unit (a.m.u.). Atomic mass unit, also known as the dalton (Da), is 1/12 of the mass of an atom of the carbon isotope 12C (~1.66 × 10−24 g). [Wikipedia]
Avogadro Constant. The Avogadro constant, often denoted NA, is the number of molecules per mole of a substance. NA = 6.02214076 × 1023 (conventionally rounded to 6.02 × 1023). [Wikipedia]
Baking Soda. Baking soda is sodium bicarbonate (sodium hydrogen carbonate), NaHCO3. [Wikipedia]
Barium Meal. Barium meal is a thick suspension of barium sulfate (BaSO4), often containing flavors and other additives, which a patient takes as a radiocontrast agent for examination of the gastrointestinal tract for abnormalities. [Wikipedia]
Base. A Brønsted-Lowry base is a molecule or ion that can serve as a proton (H+) acceptor. [Wikipedia] A Lewis base is a molecule or ion that can donate a lone electron pair to a Lewis acid. [Wikipedia]
Berthollet's Salt. Berthollet's salt is potassium chlorate, KClO3. [Wikipedia]
Binary Compound. A binary compound is a complex substance containing two different elements. [Wikipedia]
Boiling Point. The boiling point (abbreviated b.p.) of a substance is the temperature at which the vapor pressure of that substance in the liquid phase equals the pressure surrounding the liquid. The boiling point strongly depends on the surrounding pressure. The atmospheric boiling point (also known as normal boiling point) is the temperature at which the vapor pressure of the liquid equals 1 atmosphere, the atmospheric pressure at sea level. [Wikipedia]
Carbocation. A carbocation is a cation bearing the positive charge on a carbon atom. [Wikipedia]
Carbohydrate. A carbohydrate, from "hydrated carbon" (also known as saccharide or sugar) is a biomolecule with the empirical formula Cn(H2O)m. For example, glucose and fructose are isomeric carbohydrates with the formula C6H12O6 = C6(H2O)6. Sucrose, also a carbohydrate, has the formula C12H22O11 = C12(H2O)11. Some exceptions exist. For example, the empirical formula of deoxyribose, C5H10O4, does not fit the general formula Cn(H2O)m. Another exception is formaldehyde, CH2O that fits the general formula (n = m = 1), yet is not a carbohydrate. [Wikipedia]
Carbonation of Water. Carbonation of water is a process of saturating or oversaturating water with carbon dioxide, CO2, often under pressure. [Wikipedia]
Catalase. Catalase is a huge and very complex biomolecule, an enzyme that catalyses the decomposition of hydrogen peroxide to water and oxygen. [Wikipedia]
Catalysis. Catalysis is the phenomenon of acceleration of a chemical reaction by adding a small amount of a substance called a catalyst. [Wikipedia]
Catalyst. A catalyst is a substance that accelerates a chemical reaction. It is often stated that a catalyst can be recovered unchanged at the end of the reaction. More modern alternative definitions of a catalyst omit this condition. [Wikipedia]
Cathode. A cathode is the negatively charged electrode that attracts cations an electrolyte and through which the electrons are released into the electrolyte solution or melt. [Wikipedia]
Chalcogens. The chalcogens are the chemical elements of group 16 of the periodic table: oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po). [Wikipedia]
Chemical Bond. A chemical bond is an attraction between atoms or ions, which holds them together and enables the formation and existence of all but monoatomic chemical substances. [Wikipedia]
Chemical Equation. A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulas, wherein the reagent(s) are presented on the left-hand side and the product(s) on the right-hand side. [Wikipedia]
Chemical Kinetics. Chemical kinetics is the branch of chemistry that deals with rates of chemical transformations. [Wikipedia]
Chemical Reaction. A chemical reaction is a process of transformation of a substance (or a set of substances) into another substance (or a set of substances). [Wikipedia]
Chemical Structure. A chemical structure is the 3-dimensional arrangement of atoms and/or ions in a chemical substance. Connectivity, bond distances, and bond angles are the key parameters that characterize a chemical structure of a substance. [Wikipedia]
Chemiluminescence. Chemiluminescence is the release of energy exclusively or almost exclusively in the form of light in a chemical reaction. Combustion and many explosive reactions produce not only light but also a lot of heat and, therefore, do not fall in the category of chemiluminescent reactions. [Wikipedia]
Chirality. A molecule or ion is chiral if it is not superimposable with its mirror image. [Wikipedia]
Chlorophyll. Chlorophyll is the magnesium-based green pigment of plants. Chlorophyll plays a key role in photosynthesis, the light-induced process plants use to make glucose from water and atmospheric CO2. The role of chlorophyll in plants is to capture and transfer the energy from light to the reaction center of photosynthesis. [Wikipedia]
Colloidal Solution. A colloidal solution is a mixture containing colloidal particles evenly distributed throughout the system. A colloidal particle ranges between approximately 1 and 1000 nanometers (nm) in diameter, considerably larger than most simple molecules and ions. For example, the sulfate (SO42-) and carbonate (CO32-) anions are 0.35 nm and 0.51 nm in diameter, respectively. [Wikipedia]
Combination Reaction. A combination reaction is a chemical reaction between two or more substances to give a single substance. [Wikipedia]
Comproportionation. Comproportionation is a redox reaction in which two compounds containing the same element but in different oxidation states react to give a product containing the element in an intermediate oxidation state. Example: SO2 + 2 H2S = 3 S + 2 H2O. Comproportionation is opposite to disproportionation. [Wikipedia]
Crystallization. Crystallization is the phenomenon of the formation of a solid crystalline substance from its solution or melt. [Wikipedia]
Cycloalkane. Cycloalkane is a cyclic hydrocarbon devoid of multiple carbon-carbon bonds with a general formula CnH2n. [Wikipedia]
Decantation. Decantation is a simple and convenient separation technique in which a liquid over a solid material at the bottom of a vessel is gently poured off so as not to disturb the solid. [Wikipedia]
Decomposition Reaction. In a decomposition reaction, one compound breaks down into two or more other compounds. [Wikipedia]
Degree of Dissociation. The degree of dissociation is the fraction of original solute molecules that have dissociated. It is conventionally denoted by the Greek symbol α and expressed as a percentage. [Wikipedia]
Dehydration Reaction. A dehydration reaction is a chemical transformation that involves the loss of water from a compound. [Wikipedia]
Deliquescence. Deliquescence is the process by which a hygroscopic substance absorbs moisture from the atmosphere until it dissolves in the absorbed water and forms an aqueous solution. [Wikipedia]
Deprotonation. Deprotonation is the abstraction of a proton (H+) from a molecule or ion in the presence of a base. [Wikipedia]
Desiccant. A desiccant is a hygroscopic material used as a drying agent. [Wikipedia]
Dipole. In chemistry, a molecule is a dipole (from di and pole) if it bears two opposite charges separated by a certain distance. [Wikipedia]
Disproportionation. Disproportionation is a redox reaction in which one element in the same substance is simultaneously reduced and oxidized to give two different products containing the same element, one in a higher and one in a lower oxidation state. Example: Cl2 + 2 NaOH = NaCl + NaOCl + H2O. Disproportionation is opposite to comproportionation. [Wikipedia]
Distillation. Distillation is a separation and purification technique that involves the heating of a liquid to produce vapors that are then condensed back to liquid form. [Wikipedia]
Effervescence. Effervescence is the evolution and escape of gas from a solution. [Wikipedia]
Electrode. In chemistry, an electrode is an electrical conductor used to make contact between an electrolyte solution or melt and the rest of an electrical circuit. [Wikipedia]
Electrolysis. Electrolysis is a method to induce an otherwise impossible chemical transformation by passing a direct electric current through the reactant(s) in solution or in the molten state. [Wikipedia]
Electrolyte. An electrolyte is a compound that conducts electricity in the liquid (usually molten) state and/or forms an electrically conducting solution when dissolved in water. [Wikipedia]
Electrolytic Dissociation. Electrolytic dissociation, also known as ionic dissociation, is disintegration of a chemical compound into ions upon dissolution or melting. [Wikipedia]
Electron Configuration. The electron configuration is the way electrons are distributed over the shells and subshells in an atom, molecule, or ion. [Wikipedia]
Electron Shell. An electron shell is the space where the probability of finding an electron in an atom is the highest. An electron shell is often thought of as an orbit followed by electrons around an atom's nucleus. [Wikipedia]
Electronegativity. Electronegativity is a measure of the tendency of an atom in a molecule to attract a shared electron pair toward itself. [Wikipedia]
Enantiomer. An enantiomer is one of two isomers that are mirror images of each other, which are not superimposable (much as one's left and right hands). [Wikipedia]
Endothermic. A chemical reaction is endothermic if it takes in energy from the surroundings as it occurs. [Wikipedia]
Energy of Activation. Energy of activation, also known as activation energy, is the minimum quantity of energy that the molecules of reagents must have in order to undergo a specified reaction. [Wikipedia]
Epsom Salt. Epsom salt is magnesium sulfate heptahydrate, MgSO4•7H2O. [Wikipedia]
Equilibrium. A reversible chemical reaction is said to be at equilibrium when the rate of the forward transformation equals the rate of the backward transformation. [Wikipedia]
Exchange Reaction. In an exchange reaction, also known as metathesis reaction, two different compounds interchange their parts (such as ions or molecular fragments). [Wikipedia]
Exothermic. A chemical reaction is exothermic if energy in the form of heat is released as the reaction occurs. [Wikipedia]
Filter. A filter is a device used for separation of a liquid and a solid by filtration. The key part of a filter is a porous material through which only the liquid can pass. [Wikipedia]
Filtrate. Filtrate is the liquid that has passed through a filter. [Wikipedia]
Filtration. Filtration is a technique to separate a solid and liquid from their heterogeneous mixture using a filter, which only the liquid can pass through. [Wikipedia]
Fool's Gold. Fool's gold is an alternative name for the mineral pyrite, FeS2. [Wikipedia]
Functional Group. Functional groups are groups of atoms that confer certain chemical properties on all molecules of which they are a moiety. [Wikipedia]
Galvanization. Galvanization is the process of applying a zinc coating to steel in order to prevent rusting. [Wikipedia]
Glacial Acetic Acid. Glacial acetic acid is acetic acid containing no or very little water. The name originates from the fact that pure acetic acid crystallizes when placed in an ice bath, due to the melting point of ~16 oC, just below room temperature. [Wikipedia]
Half Reaction. A half reaction is either the oxidation or reduction reaction component of a redox chemical transformation. [Wikipedia]
Hemoglobin. Hemoglobin is the iron-containing protein that transports oxygen (O2) from the lung or gill to the cells of the body. [Wikipedia]
Heterogeneous Mixture. A mixture is heterogeneous if its composition differs throughout the sample. [Wikipedia]
Heterogeneous Reaction. A chemical reaction is heterogeneous if at least one reactant is located in a phase that is different from the phase containing the other reactants(s). [Wikipedia]
Heterolytic. A covalent bond cleavage is said to be heterolytic if the shared pair of electrons is taken by one of the two previously bonded atoms. [Wikipedia]
Homogeneous Mixture. A mixture is homogeneous if it displays a perfectly even distribution of its components on a molecular level throughout the sample. [Wikipedia]
Homogeneous Reaction. A chemical reaction is homogeneous if all of the reagents are located in the same phase of a reaction mixture, such as in solution or in the gas phase. [Wikipedia]
Homologue. Homologues are organic compounds that differ from one another by one or more repeating -CH2- bridge units. [Wikipedia]
Homolytic. A covalent bond cleavage is said to be homolytic if each of the two originally bonded atoms takes one of the two electrons of the shared pair in the fission process. [Wikipedia]
Hybridization. In chemistry, hybridization (or orbital hybridization) is the concept of, and a mathematical model for, mixing and averaging atomic orbitals into new hybrid orbitals suitable for the pairing of electrons to form covalent bonds. [Wikipedia]
Hydration. In inorganic and general chemistry, hydration is either a reaction in which a substance combines with water, or electrostatic interactions between ions and water dipoles in solution. In organic chemistry, a hydration reaction is a reaction in which water adds across a C=C or C≡C bond. [Wikipedia]
Hydrocarbon. A hydrocarbon is an organic compound consisting of only carbon and hydrogen atoms. [Wikipedia]
Hydrogenation. In organic chemistry, a hydrogenation reaction is a reaction of addition of hydrogen (H2) across a C=C or C≡C bond. Hydrogenation of alkenes and alkynes usually requires a catalyst to occur. [Wikipedia]
Hydrolysis. In many instances, hydrolysis is a chemical reaction in which water breaks one or more chemical bonds of an organic or inorganic compound. This definition is not applicable, however, to hydrolysis of many simple inorganic salts. The hydrolysis of salts is the reverse of the neutralization reaction that occurs, often reversibly, if the salt is derived from a weak acid or a weak base or both. [Wikipedia]
Hygroscopic. A substance is said to be hygroscopic if it takes up and retains moisture from the air. [Wikipedia]
Immiscible. Two liquids are immiscible if they form a heterogeneous mixture when blended together. For example, water and vegetable oil are immiscible. [Wikipedia]
Intramolecular and Intermolecular Reactions. An intramolecular reaction is a chemical transformation within a single molecule. An intermolecular reaction requires two or more molecules to occur. [Wikipedia]
Invertase. Invertase is an enzyme that is used in industry for the catalytic hydrolysis of sugar to make inverted sugar. [Wikipedia]
Inverted Sugar. Inverted or invert sugar is a syrup produced by hydrolysis of sucrose (sugar) to yield a mixture of glucose and fructose, which is sweeter than sugar itself. In baking, inverted sugar syrup is often preferred over sugar. [Wikipedia]
Irreversible Reaction. An irreversible reaction is a chemical transformation in which the product(s) cannot revert back into the reactant(s). [Wikipedia]
Isomer. Isomers are molecules or ions that have exactly the same composition but different structures. [Wikipedia]
Kiln. A kiln is high-temperature oven or furnace used for a variety of purposes, such as for calcining limestone via the thermal decomposition, CaCO3 = CaO + CO2. Kilns are also used for burning, drying, and firing pottery. [Wikipedia]
Laughing Gas. Laughing gas is a common name for nitrous oxide, N2O. [Wikipedia]
Limestone. Limestone is naturally occurring calcium carbonate, CaCO3. [Wikipedia]
Limewater. Limewater is a saturated solution of calcium hydroxide, Ca(OH)2. [Wikipedia]
Limiting Reagent. Of two or more reagents taking part in a chemical reaction, the limiting reagent is the one that is totally consumed after the reaction has gone to completion. The other reagent(s) are said to have been used in excess for the reaction. [Wikipedia]
Litmus Paper. Litmus paper is a broadly used acid-base indicator. Blue litmus paper changes its color to red in the presence of an acid. [Wikipedia]
Lone Electron Pair. A lone electron pair is a pair of valence electrons that occupy the same orbital and that are not shared with other atoms. [Wikipedia]
Mass Percentage Concentration. The mass percentage (percent) concentration shows the number of grams of a solute in 100 grams of solution. [Wikipedia]
Matter. Everything that has a volume and mass is matter. The three main states of matter are solid, liquid, and gas. [Wikipedia]
Melting Point. The melting point (abbreviated m.p.) is the temperature at which a solid substance melts. The melting point of a substance is the same as its freezing point, the temperature at which the same substance in the liquid state solidifies. Melting/freezing points are conventionally measured and specified at a standard pressure of 1 atmosphere ≈ 1 bar. [Wikipedia]
Metal. A metal is a chemical element whose atoms form a simple substance that is: (1) a good conductor of electricity and heat; (2) ductile and malleable; and (3) lustrous on clean surface. A metal is as an element that readily forms positively charged ions by willingly giving away its valence electron(s) to attain the stable ns2np6 (octet) electron configuration. A metal atom usually has one, two, or sometimes three (at the most) electrons in its valence shell. [Wikipedia]
Metalloid. The term "metalloid" is loosely defined as a chemical element that forms a simple substance displaying properties intermediate between those of a typical metal and a typical nonmetal. [Wikipedia]
Micelle. A micelle is an aggregate of molecules dispersed in a colloidal solution, such as those formed by soap and microdroplets of oils or fats. [Wikipedia]
Milk of Lime. A suspension of Ca(OH)2 in its saturated solution (limewater). [Wikipedia]
Miscible. Two liquids are miscible if they can form a homogeneous mixture when blended together. For example, alcohol (ethanol) and water are miscible. [Wikipedia]
Mixture. A mixture is matter comprising two or more substances. [Wikipedia]
Molar Concentration. The molar concentration, also known as molarity, shows the number of moles of a solute in 1 liter of solution. [Wikipedia]
Mole. The mole (abbreviated mol) is the unit of quantity of substance that contains 6.02 × 1023 molecules. [Wikipedia]
Molecule. A molecule is an electroneutral (having no net electric charge) group of atoms held together by chemical bonds. (It is often said that the noble gases (He, Ne, Ar, Kr, Xe, and Rn) consist of monoatomic molecules.) A molecule is the smallest unit of a pure substance that retains the composition and most chemical properties of that substance. I say "most" rather than "all" because in some cases more than one molecule of a given substance is needed to exhibit a particular chemical property. As an example, the decomposition of nitric acid according to the equation, 4 HNO3 = 2 H2O + 4 NO2 + O2, requires at least four molecules of HNO3 to take place. Likewise, at least two molecules of NO2 are needed for the dimerization reaction of nitrogen dioxide, 2 NO2 = N2O4. [Wikipedia]
Mother Liquor. A mother liquor is the part of a solution that is left over after crystallization. [Wikipedia]
Muriatic Acid. Muriatic acid is an alternative name for hydrochloric acid, a solution of hydrogen chloride, HCl, in water. [Wikipedia]
Nanoparticles. A nanoparticle is a particle of matter ranging between 1 and 100 nanometers in diameter. Nanoparticles are a subclass of colloidal particles. [Wikipedia]
Neutralization Reaction. A neutralization reaction is the reaction between an acid and a base to give a salt and water. [Wikipedia]
Nomenclature. A chemical nomenclature is a set of rules for naming chemical substances. [Wikipedia]
Nonmetal. A nonmetal is a chemical element whose atoms form a simple substance that mostly lacks the key characteristics and physical properties of metals. Atoms of a nonmetal are not prone to form cations by giving away their electrons. Typically, a nonmetal atom has more than three valence electrons. [Wikipedia]
Octet Rule. The octet rule states that atoms tend to have eight valence electrons or, in other words, seek to attain the stable electron configuration of a noble gas. [Wikipedia]
Orbital. An orbital is a subshell within a given electron shell. An orbital can accommodate no more than two electrons. [Wikipedia]
Oxidant. An oxidant (also known as oxidizing agent or oxidizer) is a substance that gains electrons in a chemical reaction. It is also an atom in a molecule or ion that gains electrons and/or changes its oxidation state to a lower one in a redox process. [Wikipedia]
Oxidation. Oxidation is a process in which an atom or ion loses electrons and/or changes its oxidation state to a higher one. [Wikipedia]
Oxidation State. The oxidation state (also known as oxidation number) is the conceptual positive, negative, or zero charge that an atom would have if all of the covalent bonds to that atom were heterolytically cleaved by fully shifting all of the shared electron pairs to the more electronegative atoms. [Wikipedia]
Paraffin. Paraffins is an alternative name for alkanes. [Wikipedia]
Petrochemistry. Petrochemistry is the branch of chemistry that studies transformations of crude oil and natural gas. [Wikipedia]
Phase Transition. A phase transition is the physical phenomenon of transformation of one state of matter for a substance into another one. As an example, the melting of ice (solid H2O) to water (liquid H2O) is a phase transition. [Wikipedia]
Phenolphthalein. Phenolphthalein is a chemical compound that is broadly used as an acid-base indicator. A solution of phenolphthalein is colorless in the presence of an acid but turns pink in the presence of a base. [Wikipedia]
Pig Iron. Pig iron is the crude iron obtained by smelting iron ores in a blast furnace. Pig iron contains up to 5% carbon as well as other impurities and is too brittle to be used directly as a material for most applications. [Wikipedia]
Pnictogens. The pnictogens are the chemical elements of group 15 of the periodic table: nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi). [Wikipedia]
Polarization. Polarization is the shifting of the shared electron pair constituting a covalent bond between two atoms toward the more electronegative one. [Wikipedia]
Polycondensation. Polycondensation is a polymerization reaction that produces a polymer and small molecules such as water. [Wikipedia]
Polymer. A polymer, also called a macromolecule, is a large molecule consisting of many repeating units bonded to one another by chemical bonds. [Wikipedia]
Polymerization. Polymerization is a chemical reaction that produces a polymer from small molecules, called monomers in this context. [Wikipedia]
Polyol. A polyol is an alcohol containing two or more OH groups within the molecule. An alcohol with two OH groups on the molecule is a diol and with three OH groups is a triol. [Wikipedia]
Product. In chemistry, a product is a substance produced as a result of a chemical reaction. [Wikipedia]
Pyrophoric. A substance or a mixture of substances is pyrophoric if it ignites spontaneously on exposure to air. [Wikipedia]
Quicklime. Quicklime is calcium oxide (CaO) produced by thermal decomposition (calcination) of limestone. [Wikipedia]
Radicals. A radical, sometimes called a free radical, is a molecule that contains at least one unpaired valence electron. [Wikipedia]
Reactivity. Reactivity of a substance is its ability to engage in a particular chemical reaction. [Wikipedia]
Reagent or Reactant. A reagent is a substance consumed in a chemical reaction. A reagent is often called a reactant or, especially in synthetic organic chemistry, a starting material. [Wikipedia]
Recrystallization. Recrystallization is a separation and purification technique that involves the dissolution of a solid substance to be purified in water or another solvent, followed by crystallization of a solid from the resultant solution. [Wikipedia]
Redox Reaction. A redox reaction is a chemical reaction that involves changes in the oxidation states of atoms. [Wikipedia]
Reductant. A reductant (also known as reducing agent, also known as reducer) is a substance that loses electrons in a chemical reaction. It is also an atom in a molecule or ion that loses electrons and/or changes its oxidation state to a higher one in a redox process. [Wikipedia]
Reduction. Reduction is a process in which an atom or ion gains electrons and/or changes its oxidation state to a lower one. [Wikipedia]
Reversible Reaction. A reversible reaction is a chemical transformation that can proceed both forward and backward. [Wikipedia]
Room Temperature. Room temperature (also known as ambient temperature) is a colloquial term for the air temperature inside a specific room or building. In spite of its ambiguity, the term "room temperature" is quite broadly used in chemistry, conventionally meaning a temperature around 23 oC. [Wikipedia]
Saltpeter. Saltpeter is a common name for potassium nitrate, KNO3 (Indian saltpeter or just saltpeter), and sodium nitrite, NaNO3 (Chilean saltpeter). [Wikipedia]
Saponification. Saponification is a process of making soap by alkaline hydrolysis of oils or fats in the presence of NaOH or KOH. Sometimes alkaline hydrolysis of esters other than fats and oils is also referred to as saponification. [Wikipedia]
Saturated Hydrocarbon. A saturated hydrocarbon is a hydrocarbon devoid of multiple (C=C or C≡C) carbon-carbon bonds. A saturated hydrocarbon can be an alkane or a cycloalkane. [Wikipedia]
Saturated Solution. A saturated solution is the solution that contains the maximum possible amount of a given substance in a particular amount of a given solvent under particular conditions (temperature and pressure). [Wikipedia]
Semiconductor. A semiconductor is a substance that conducts electricity worse than metals but better than insulators such as polyethylene, wood, or glass. [Wikipedia]
Shared Electron Pair. A shared electron pair is the two valence electrons that constitute one covalent bond between two atoms. [Wikipedia]
Silica. Silica is an alternative name for silicon dioxide, SiO2. [Wikipedia]
Silica Gel. Silica gel is amorphous and porous silica, SiO2. Silica gel is a broadly used desiccant and adsorbent. [Wikipedia]
Slaked Lime. Slaked lime is calcium hydroxide, Ca(OH)2, produced by reacting quicklime (CaO) with water. [Wikipedia]
Solubility. Solubility is the ability of a solid, liquid or gaseous substance to dissolve in a solvent at a specified temperature and pressure. [Wikipedia]
Solute. A solute is the solid, liquid or gaseous substance that is dissolved in a solvent. For example, in a brine solution, salt (NaCl) is the solute and water is the solvent. [Wikipedia]
Solvent. A solvent is a liquid that dissolves a solute. [Wikipedia]
Standard Temperature and Pressure (STP). STP is defined as 0 oC and 1 bar (= 1.01325 atm.). [Wikipedia]
Stoichiometry. Stoichiometry is the ratio in which reagents take part in a particular chemical reaction. In other words, stoichiometry is the relationship between the amounts of substances that react together in a particular chemical reaction and the amounts of products formed in that reaction. [Wikipedia]
Sublimation. Sublimation is the phase transition of a substance from the solid state directly to the gas phase (vapor), without melting. Examples of substances that sublime include iodine (I2) and dry ice (solid carbon dioxide, CO2). Wikipedia
Substitution Reaction. In a substitution reaction (also known as displacement reaction), one atom or group of atoms of a molecule is replaced with another atom or group of atoms. [Wikipedia]
Substance. A substance is matter composed of molecules of one type. [Wikipedia]
Complex Substance. A complex substance, also known as "compound" is matter that consists of identical molecules composed of more than one element. Examples: NaCl, H2SO4, KNO3, Ca(HCO3)2, CH4.

Simple Substance. A simple substance is matter that consists of identical molecules composed of only one element. Examples: O2, O3, P4, He, H2, N2, Cl2.

Individual Substance. This term is used to emphasize that a substance is free from other substances.
Synthetic. An artificial material made by targeted chemical synthesis. In terms of chemical, physical, biological, etc. properties, there is no difference whatsoever between a man-made molecule and the same molecule occurring in nature. For example, synthetic vitamin C (ascorbic acid) and formic acid are 100% identical with those produced by living organisms. [Wikipedia]
Thermite. Thermite is a mixture of aluminum powder (Al) and iron oxide (Fe2O3). If ignited, the mixture is engaged in a highly exothermic reaction that produces aluminum oxide (Al2O3) and iron metal (Fe). Thermites based on other metals and metal oxides are known. [Wikipedia]
Tin Pest. Tin pest (also known as tin disease, tin plague, tin blight or tin leprosy) is the phase transition of the most common allotrope of tin metal (β-tin or white tin) to the brittle nonmetallic allotropic form of tin (α-tin or grey tin). Tin pest occurs at 13 oC and below. [Wikipedia]
Tinning. Tinning is the process of applying a tin coating to steel in order to prevent rusting. [Wikipedia]
Tinplate. Tinplate is sheets of steel coated with a thin layer of tin. [Wikipedia]
Transition Metal. A transition metal is an element whose atom has partially filled d-orbitals. [Wikipedia]
Unsaturated Hydrocarbon. An unsaturated hydrocarbon is a hydrocarbon containing one or more C=C double bonds and/or C≡C triple bonds. [Wikipedia]
Valence. Valence is a measure of the capacity of a chemical element to combine with a certain number of atoms of other elements in chemical reactions. [Wikipedia]
Valence Electrons. A valence electron is an electron occupying the outermost shell of an atom. If the outermost shell is not fully filled with electrons, they can participate in the formation of a chemical bond. [Wikipedia]
Vinegar. Vinegar is a 3-8% aqueous solution of acetic acid, CH3COOH. [Wikipedia]
Viscous. A liquid is said to be viscous if it has a thick, syrup-like consistency. [Wikipedia]
Water of Crystallization. Water of crystallization are the molecules of water present inside crystals. Many, but not all, inorganic salts crystallize out of aqueous solutions in the form of crystal hydrates that contain molecules of water in the crystal lattice. For example, copper sulfate crystallizes from water in the form of the pentahydrate, CuSO4•5H2O, containing five molecules of water of crystallization per CuSO4 unit. [Wikipedia]
Xanthoproteic Reaction. The xanthoproteic reaction is an old test to detect proteins. A colorless protein-containing solution turns yellow on addition of nitric acid. The color change is due to the formation of yellow nitroaromatic compounds formed in the nitration of the amino acid units bearing an aromatic ring, such as tyrosine and tryptophan. [Wikipedia]
Zwitterion. A zwitterion, also known as inner salt, is a molecule that has a cationic (positively charged) and anionic (negatively charged) centers. [Wikipedia]