Title Class XII Chemistry Glossary.pdf ✅

Abnormal molar mass: The value of molar mass that is higher or lower than the true value. Absorption: A bulk phenomenon in which the concentration of molecular species is uniformly distributed throughout the body of the solid or liquid. Actinoids: The 15 metallic elements between actinium and lawrencium. Activated carbon: An extremely porous carbon that has a very large surface area available for adsorption or chemical reactions. Activated complex: An unstable intermediate complex formed by the collision of reactant molecules which ultimately breaks to form products. Activation energy: The minimum energy required to form the activated complex. Active site of enzymes: A site present on the enzyme which binds its specific substrate and hence forms enzyme–substrate complex. Addition polymerization:A polymerization reaction in which monomers containing one or more double bonds are linked to each other without the elimination of any byproducts, usu- ally in the presence of free radical initiator. Adsorbate: The gas or solution which is adsorbed the surface. Adsorbent: The solid or liquid on whose surface, gas or liquid is adsorbed. Adsorption: The phenomenon of the assimilation of higher concentration of any species at the surface of a solid or liquid as compared to that present in the bulk of the material. Adsorption chromatography: A technique used for the sep- aration of compounds based on their selective adsorption on the surface of a suitable adsorbent. Adsorption isobar: A curve showing variation of adsorption with temperature at constant pressure. Adsorption isotherm: A curve showing the variation in of adsorption with pressure at constant temperature. Agonist: The drug which binds to a receptor and mimics the effect of natural messenger thus helping in signal transmission. AIDS (acquired immuno deficiency syndrome): A severe disease of immune system which is caused by special type of virus called as human immuno deficiency virus (HIV). Alcohols: The compounds whose molecules have one or more hydroxyl groups attached to a carbon atom. Aldaric acids: These are sugar acids where the terminal hydroxyl groups have been replaced by carboxylic acids. Aldehydes: Compounds containing a carbonyl group (carbon double bonded to oxygen) bonded to hydrogen and an alkyl group. Aldol condensation: An organic reaction in which an enolate ion reacts with a carbonyl compound to form a b-hydroxyaldehyde or b-hydroxyketone, followed by dehy- dration to give a conjugated enone. Aliphatic amines: Amines in which all the carbon atoms bonded directly to nitrogen are derived from alkyl groups. Alkyl group: A functional group which consists of single bonded carbon and hydrogen atoms. Alkyl halides: The compounds in which a halogen atom replaces a hydrogen atom of an alkane. Alkylidene: Divalent functional group derived from alkane by removal of two hydrogen atoms from the same carbon atom. Allosteric inhibition: The inhibition in which the interaction of an enzyme molecule with a drug is at a site other than the active site. Allylic alcohols: The compounds with carbon atom bonded to –OH is attached to carbon–carbon double bond. Allylic halides: The compounds with halogen atom bonded to carbon atom next to a carbon–carbon double bond. Ambidentate ligands: The ligands capable of ligating through two different atoms. Amides: An organic compound containing the group CONH2 . Amines: The derivatives of ammonia (NH3 ) in which one or more hydrogen atoms are replaced by alkyl or aryl groups. Amino acids: These are compounds containing an amine group and a carboxylic group. a -Amino acids are carboxylic acids that contain an amino (–NH2 ) group attached to C2 (the a-carbon). Amorphous solids: The solids that do not have a definite geometrical shape. Analgesics: The drugs used to relieve pain. Analytical chemistry: The study of separation, identification, and quantification of the chemical components of natural and artificial materials. Anionic complex: A negatively charged complex ion. Anionic detergents: The detergents having a negative ionic group and are sodium salts of sulphonated long-chain alcohols or hydrocarbons (e.g., sodium salts of alkylbenzene- sulphonates). Anisotropy: The molecules exhibiting different values for physical properties when measured in different directions. Anode: The electrode at which oxidation (loss of electrons) takes place during an electrochemical charge. Glossary Downloaded from newtonclasses.net Office.: 606 , 6th Floor, Hariom Tower, Circular Road, Ranchi-1, Ph.: 0651-2562523, 9835508812, 8507613968 www.newtonclasses.net
2 Anomers: Monosaccharides that differ in configuration only at anomeric carbon, that is the hemiacetal carbon of the cyclic form. Antacids: The drugs which neutralize the acidity in stomach. Antagonists: The drugs which bind to the receptor site and inhibit its natural function. Antibiotics: The drugs that restrict the growth of microorgan- isms and prevent spread of infection. Anticatalyst: A substance which deactivates the catalyst. Antiferromagnetic: A substance with zero net magnetization since the adjacent dipoles point in opposite directions. Antifertility drugs: The drugs capable of reducing or elimi- nating fertility and thereby helping in birth control. Antihistaminic drugs: The drugs that inhibit action of hista- mine. Anti-Markovnikov addition: An addition reaction in which the hydrogen atom is added to more substituted carbon atom of the double bond while the halogen (or any other group) is added to less substituted carbon. It generally takes place in presence of peroxides. Antimicrobials: The substances that either kill microbes (microbiocidal) or prevent microbial growth (microbiostatic). Antiseptic: The chemical substances that prevent the growth of microorganisms or kill them but are not harmful when applied to human tissues. Aprotic solvent: A solvent that does not exchange protons with a substance dissolved in it. Aromatic amines: Amines in which one or more of the groups bonded directly to nitrogen are aryl groups. Arrhenius theory: The reactant molecules are first converted into a highly energized intermediate activated complex or transition state, which further breaks down into products. Artificial sweetening agents: The chemical agents respon- sible for sweetening of edible food materials. Aryl halides: The compounds with halogen attached to sp2 hybridized carbon atom of aromatic ring. Associated colloids: The colloids in which the dispersed phase is made up of particles that behave as regular electro- lytes at lower concentrations but aggregate at higher concen- trations to form particles of colloidal dimension. Asymmetric carbon atom: The carbon atom attached to four different functional groups or atoms. Azeotropic mixtures: The liquid solutions of two (or more) components which have a composition that does not change on distillation. Azo dye: These are compounds of the form Ar ArN N which are formed by azo coupling reaction and are commonly used as dyes. Bakelite: A thermosetting phenol–formaldehyde resin made by a condensation reaction between phenol and formalde- hyde; the reaction can be catalyzed by either acids or bases. Battery: A combination of cells either in series or parallel or both, in which chemical energy is converted into electrical energy. Benefaction of ore: A method for concentration of ore to separate out gangue and other impurities from the metal. Benzylic alcohols: The compounds with carbon atom bonded to –OH, attached to an aromatic ring. Benzylic halides: The compounds with halogen atom bonded to carbon atom attached to an aromatic ring. Bimolecular reactions: The reactions which involve two molecular species as reactants. Binary solution: A mixture of solute and solvent. Biocolloids: The colloidal mixtures of plant and animal origin. Biopolymers: The polymers such as polysaccharides (starch and cellulose), proteins, nucleic acids, etc. which can undergo natural degradation by the action of naturally occurring microorganisms, such as bacteria, fungi and algae. Blast furnace: A metallurgical furnace used in the process of smelting to produce industrial metals, generally iron. Body-centered unit cell: A unit cell where atoms are present at its corners and one at the center. Bond length: The average distance between the nuclei of two bonded atoms. Branched-chain polymers: The polymers contain molecules having a linear backbone with branches arising randomly from it. Branched-chain polymer is formed when a bifunc- tional monomer is mixed and polymerized with a little amount of trifunctional monomer. Bredig’s arc method: A method used for the preparation of colloids of metals such as gold, silver, copper, platinum, etc. Brownian movement: The random motion of colloidal par- ticles due to continuous bombardment of the dispersed par- ticles by the dispersion medium. Calcination: A process in which the concentrated ore is heated to a high temperature (just below its fusion tempera- ture) in the absence of air (or limited supply of air) causing loss of moisture, reduction or oxidation, and the decomposition of carbonates and other compounds. Cannizzaro reaction: A reaction involving disproportionation of aldehydes lacking a-hydrogens in the presence of a strong base to form salt of an acid and a corresponding primary alcohol. Carbohydrates: Polyhydroxy aldehydes and ketones or sub- stances that hydrolyze to yield polyhydroxy aldehydes and ketones. General formula Cn H2nOn . Carbonyl group: A group containing carbon–oxygen double bond, C O. Carboxylic acids: The organic acids possessing at least one carboxyl group. Cast iron: It is a purer form of iron obtained by re-melting pig iron. The two main alloying elements present are carbon (2.1 to 4 % by weight) and silicon (1 to 3 % by weight). Catalyst: A substance which alters the rate of a chemical reac- tion without itself getting consumed in the reaction. Catalytic hydrogenation: An process which involves addi- tion of molecular hydrogen to a double bond in presence of a metal catalyst. 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Cathode: The electrode at which reduction (gain of electrons) takes place during an electrochemical change. Cathodic protection: It is process in which a structural metal, such as iron, is protected from corrosion by connecting it to a metal that has more negative reduction half-cell potential. The entire metal is then converted into a cathodic site where the corrosion does not take place. Cationic complex: A positively charged complex ion. Cationic detergents: The detergents having a long hydrocar- bon chain and a positive charge. The active part of the mol- ecule is the cation and these are generally quaternary ammo- nium salts. Cell potential: The potential difference between the two elec- trodes. It corresponds to the maximum potential that a cell can generate. Cellulose: A polysaccharide consisting of D-glucopyrano- side units linked in (1 → 4) fashion in very long unbranched chains. Centered or non-primitive unit cell: A unit cell where atoms (lattice points) are present not only at the corner of unit cells but also at some other positions. Central atom/ion: The central cation that is surrounded and coordinately bonded to one or more neutral molecules or negatively charged ions in a definite geometric arrange- ment. Chelate complexes: The complexes of polydentate ligands. Chemical kinetics: The study of the speeds (or rates) of chem- ical reactions. Chemisorption: A process involving chemical bond forma- tion between adsorbate and adsorbent. Chemotherapy: The branch of science which deals with the treatment of various diseases with suitable chemical substances. Chiral molecule: A type of molecule that lacks an internal plane of symmetry and thus has a non-superimposable mirror image. Chloramphenicol: A chlorine containing antibiotic, produced by soil organism, which is used for treating typhoid. Chromatography: A method of separating a mixture of components into individual components by equilibrium distribution between the two phases. Chromosomes: The coiled structures of DNA and protein which contain genes and other regulatory elements respon- sible for transfer of hereditary information. Cis isomers: The stereo isomer in which the two groups lie on the same side of reference plane (double bond). Cleansing agents: The substances used to remove dirt, stain, bad odor from the surface. Clemmensen reduction: A reaction involving reduction of aldehydes and ketones to the corresponding hydrocarbons with amalgamated zinc and concentrated hydrochloric acid. Coagulation: A process of setting of colloidal particles due to neutralization of charge leading to aggregation of the particles. Coinage metals: A group of three malleable ductile transition metals, that is copper (Cu), silver (Ag) and gold (Au). Colligative properties: The properties that depend only on the number of solute particles in a solution, but are indepen- dent of the nature of those particles. Collision theory: A theory stating that the rate of a reaction is proportional to the number of effective collisions per second among the reactant molecules. Colloid: A dispersion in which the dispersed particles are larger than the solute ions or molecules of a true solution and smaller than the particles of a mechanical suspension. Competitive inhibitors: The drugs in which enzyme inhibi- tor (drug) and substrate compete for the same active site and prevent the substrate from binding to the enzyme. Complex reactions: The reactions that involve more than one step. Concentrated solution: A solution with relatively large amount of dissolved solute. Concerted reactions: The reactions in which bond breakage and formation occurs in one single step. Condensation polymers: The polymers formed by intermo- lecular condensation reaction by the functional groups of monomers with continuous elimination of byproducts. Conductors: The substances that allow the passage of current through them. Consecutive reactions: These are reactions that take place in a series of steps. Coordination compounds: A special class of compounds that consist of a central metal atom or ion, which is surrounded by oppositely charged ions or neutral molecules in more than its normal valence. Coordination entity: The central metal atom or ion which is bonded to a definite number of ions or molecules which is fixed. Coordination isomerism: Occurs in those complexes which have both anionic as well as cationic entities and there is a difference in the distribution of ligands within these entities. Coordination number: The total number of ligands coordi- nately bonded to the central metal atom or ion. Coordination polyhedron: The spatial arrangement of the ligand atoms that are directly attached to the central atom/ion. Coordination sphere: This is represented by the central metal ion and the ligands coordinately bonded to it. It does not lose its identity and is non-ionizable. Copolymerization: The polymerization of two or more different monomers resulting in the formation of a polymer containing both monomers linked in one chain. Corrosion: The deterioration of materials by chemical interac- tion with their environment. Counter ions: These are ions that are not part of the coordina- tion sphere. They balance the charge on a cationic or anionic complex ion. Downloaded from newtonclasses.net Office.: 606 , 6th Floor, Hariom Tower, Circular Road, Ranchi-1, Ph.: 0651-2562523, 9835508812, 8507613968 www.newtonclasses.net