Chemistry Class 10 Important Definitions – FBISE, KPK, Punjab, Sindh, Baluchistan and Azad Kashmir Boards

Chemistry 10th          Important Definitions

  • Chemical Equilibrium:A state in a reversible reaction where the rate of forward reaction and reverse reaction becomes equal is called Chemical equilibrium.
  • Reversible reaction:The reaction in which the products recombine to form reactants is called reversible reaction.  OR  the reaction that proceed both in forward as well as reverse direction is called reversible reaction.
  • Irreversible reaction:The reaction in which the products donot recombine to form recreants is called irreversible reaction.  OR  the reaction that proceed only in forward in forward direction.

  • Static equilibrium:A chemical equilibrium in which the reaction ceases to proceed is called Static equilibrium.
  • Dynamic equilibrium;A state in chemical equilibrium where the reaction does not stop , only the rate of forward reaction becomes equal to the rate of reverse reaction is called dynamic equilibrium.
  • Reactants:The substances that combine in a chemical reaction are called reactants.
  • Products:The new substances formed after completion of a chemical reaction are called products.
  • Closed System:A system in which the substances can neither leave nor enter is called Closed system.
  • Open system:A system in which other substances enter or some some substance leave the system is called open system.
  • Law of mass action:The rate at which a substance reacts is directly proportional to its active mass and the rate of reaction is directly proportional to the product of the active masses of the reacting substances.
  • Equilibrium constant:Equilibrium constant is a ratio of the product of concentration of products raised to the power of coefficient to the product of concentration of reactants raised to the power of coefficient as expressed in the balanced chemical equation.
  • Complete reaction:A reaction in which all reactants have been fully converted into products is called complete reaction.
  • Incomplete reaction:A reaction in which all reactants have not been fully converted into products is called incomplete reaction.
  • Arrhenius concept:According to Arrhenius concept acid is a substance which dissociates in aqueous solution to give hydrogen ions, while bases are substances which dissociates in aqueous solution to give hydroxide ions.
  • Bronsted-Lowry concept:According to this concept an acid is a substance that can donate a proton (H+) to another substance while a base is a substance that can accept a proton (H+) from another substance.
  • Lewis concept:According to lewis concept “ An acid is a substance (molecule or ion ) which can accept a pair of electrons while base is a substance (molecule or ion) which can donate a pair of electrons.
  • Conjugate acid:Conjugate acid is a specie formed by accepting a proton by a base. Example: H3O+.
  • Conjugate base: A conjugate base is a substance formed by donating a proton by an acid. Example: CH3COO .
  • Amphoteric substance:A substance that can behave as an acid acid as well as a base is called amphoteric substance. Example: Water.
  • Indicator: Indicator is a chemical material that is used for the identification of acids and bases.
  • Litmus paper:Paper stained with litmus used for indication of acids and bases.
  • Litmus:Litmus is a mixture of water soluble dyes extracted from the lichens.
  • Salt:Salts are ionic compounds formed by neutralization of an acid and a base. Example: Sodium chloride (NaCl).
  • Normal OR neutral salt :A salt formed by the total replacement of ionizeable H+ ions of an acid by a positive metal ion or NH4+ ions is called normal or neutral salt. Example: KCl, NaCL, etc.
  • Acidic Salts:These salts are formed by partial replacement of H+ ion of an acid by a positive metal ion. Examples KHSO4.
  • Basic salts:The salts formed by incomplete neutralization of a polyhydroxy base by an acid. Example: Al (OH)2
  • Double salt:Double salts are formed by two normal salts when they are crystallized from a mixture of equimolar saturated solutions. Example: Ferric alum K2SO4.Fe2(SO4)3.H2
  • Mixed salts:Mixed salts contain more than one basic or acidic radicals. Example: Bleaching powder Ca(OCl)Cl.
  • Complex salts:Complex salts on dissociation provides a simple cation and a complex anion or simple anion and a complex cation. Example: Potassium ferrocyanide K4[Fe(CN)6] gives on ionization , a simple cation K+ and complex anion [Fe(CN)6]-4.
  • Organic chemistry:The branch of chemistry which deals with the study of hydrocarbons and their derivatives is known as organic chemistry.
  • Organic Compounds:Organic compounds are hydrocarbons (compounds of carbon and hydrogen) and their derivatives. Example: Glucose (C6H12O6).
  • Molecular formula:The formula which represents the actual number of atoms in one molecule of a compound. Molecular formula of butane is C4H10.
  • Structural formula:Structural formula of a compound represents the exact arrangement of the different atoms of various elements present in a molecule of a substance. Example: Structural formulas of butane is

 

 

  • Condensed formula:The formula that indicates the group of atoms joined together to each carbon atom in a straight chain or in a branched chain is called condensed formula.

 

 

  • Electronic OR Dot and cross formula:The formula which shows the sharing of electrons between various atoms in one molecule of a compound is called electronic OR Dot and cross formula. Example: Electronic formula of ethane is:

 

  • Open chain or Acyclic compounds:Open chain compounds are those organic compounds in which the end carbon atoms are not joined with each other and in this way they form a long chain of carbon atoms.Example : n_butane.

 

 

  • Closed chain OR Cyclic compounds:The closed chain or cyclic compounds are those in which the end carbon atoms are not free and they are linked to form a ring. Example : Benzene.

 

  • Catenation:The ability of carbon atoms to link with other carbon atoms to form long chains and large rings is called catenation.
  • Isomers: The compounds that have the same the same molecular formula but different arrangement of atoms in their molecules or different structural formulae are called isomers. Example: Glucose and Fructose both have formulas C6H12O6.
  • Isomerism:The existance of two or more compounds having the same molecular formulae but different arrangement of atoms within the molecules is called isomerism.
  • Distillation:The evaporation and subsequent condensation of a liquid for the purpose of purification is called distillation.
  • Homologous series: A series or group of organic compounds that have same chemical properties is called homologous series. OR  A series of organic compounds that is differ from each other by a CH2(Methylene) is called homologous series. Methane (CH4) and Ethane (C2H6) are differ from each other by a CH2
  • Functional group:An atom or group of atoms or presence of double or triple bond which determines the characteristic properties of an organic compound is called functional group. Example: Alcoholic group (OH).
  • Hydrocarbons:Hydrocarbons are those compounds which are made up of only carbon and hydrogen elements. Example: Benzene (C6H6).
  • Saturated hydrocarbons:The hydrocarbons in which all the four valencies of carbon atoms are fully satisfied (saturated) by single bonds with other carbon atoms and hydrogen atoms are called saturated hydrocarbons OR alkanes. Example: Methane (CH4).
  • Unsaturated hydrocarbons:The hydrocarbons in which two carbon atoms are linked by a double or triple bond are known as unsaturated hydrocarbons. OR hydrocarbons that have atleast one double or triple bond are called unsaturated hydrocarbons. These are of two types , alkenes and alkynes.
  • Alkenes:Hydrocarbons that have atleast one double bond are called alkenes. Examples: Ethene (C2H4).

 

  • Alkynes:Hydrocarbons that have atleast one triple bond are called alkynes. Example: Ethyne ( C2H2).

 

  • Hydrogenation:The addition of molecular hydrogn to any substance is called hydrogenation. C2H4 + H2 → C2H6.
  • Reduction:The addition of nascent hydrogen is called reduction. OR  The removal of oxygen is called reduction. OR  The gain of electrons is called reduction.
  • Oxidation:The addition of oxygen is called oxidation.  OR  The romoval of hydrogen is called oxidation.  OR  The loss of electrons is called oxidation.
  • Alkyl group : A group formed by the removal of a hydrogen atom from an alkane is called alkyl group. Example: Methyl(CH3) formed by removal of one hydrogen from methane (CH4).   .
  • Halogenation:The addition of halogen (chlorine, fluorine, Bromine) to a substance is called halogenation.

 

 

  • Hydrohalogenation:The addition of hydrogen and halogen at the same time to a substance is called hydrohalogenation. OR  The addition of hydrogen halides with other substances is called hydrohalogenation.

 

  • Dehalogenation:The removal of halogens (Chlorine , Fluorine, Bromine) to a substance is called is called dehalogenation.

 

 

  • Carbohydrates:polyhydroxy aldehydes OR polyhydroxy ketones or their derivatives are called carbohydrates.
  • Monosaccharides:(mono means one and saccharon means sugar) Monosaccharides are simplist sugars consists of only one sugar unit. Example: Glucose (C6H12O6).
  • Oligosaccharides:(Oligo means few) carbohydrates composed of 2 to 9 unit of monosaccharides are called oligosaccharides. Example: Sucrose (C12H22O11).
  • Polysaccharides:(poly means many) carbohydrates composed of more than 9 sugar units are called polysaccharides. Example: starch contain 500 to 2 million sugar units.
  • Proteins:Highly complicated nitrogenous compounds made up of amino acids are called protons.  OR  Biopolymers of amino acids are called proteins.
  • Lipids:Macromolecules made up of fatty acids are called lipids.
  • Nucleic acids:Long chain molecule made of nucleotides are called nucleic acids.
  • Deoxyribonucleic acid:A long double stranded molecule responsible for transmitting genetic information is called DNA.  OR  The type of nucleic acid that is composed of deoxyribonucleotides is called DNA.
  • Ribonuceic acid:A single stranded molecule responsible for the formation of proteins is called RNA.  OR  The type of nucleic acid that is composed ribonucleotides is called RNA.
  • Vitamin :Any of a group of organic compounds which are essential for normal growth and nutrition , required in very less quantities and protect body from various disorders.
  • Atmosphere:The envelope of different gases around the earth is called atmosphere.
  • Pollution:Any undesireable channge in the physical , chemical or Biological characteristic of air, water and land (soil) is called pollution.
  • Pollutants:A polutant is a waste material that pollutes air, water or soil.
  • Global warming (Green house effect) :The increase in temperature of atmosphere and earth due to trapping of heat energy by green house gases (CO2, etc) is called Global warming
  • Capillary action:The process by which water rises up from the roots of plants to leaves is called Capillary action.
  • Heat capacity (Specific heat) :The amount of heat required per unit mass (per gram) to raise the temperature by one degree centigrade. Example : Water has heat capacity of 4.186 Joules/gram.
  • Hydrogen bonding:The type of intermolecular forces present between hydrogen and high electronegative atoms like Fluorine, Nitrogen and Oxygen.is called Hydrogen bonding.
  • Soft water:Soft water is that which produces good lather with soap.
  • Hard water:Hard water is that which doesnot produces lather with soap.
  • Water born infectious diseases:Diseases that spread because of drinking polluted water or eating food prepared with polluted water are called water born infectious diseases. Example : Diarrhea.
  • Sewage water:Used water is called sewage water.
  • Chemical industries: Industries that turns raw materials like coal, salts, etc into a variety of products like caustic soda, detergents, etc are called chemical industries.
  • Industrial chemistry:The branch of chemistry that deals with the manufacturing of chemicals on commercial scale is called industrial chemistry.
  • Minerals:The solid natural materials found beneath the Earth’s surface, which contains compounds of metals in the combined state along with earthly impurities, are called minerals.
  • Ores : Those minerals from which the metals are extracted commercially at a comparatively low cost with minimum effort are called ores of the metals. For example: ores of copper are; copper glance (Cu2S) and chalcopyrite (CuFeS2).
  • Gangue : The earthly and other impurities associated with the minerals are known as gangue.
  • Metallurgy :The process of extraction of a metal in a pure state on a large scale from its ore by physical or chemical means is called metallurgy.
  • Concentration of the Ore:The process of removal of gangue from the ore is technically known as concentration and the purified ore is called the concentrate.
  • Gravity separation:Gravity separation is based on the differences in densities of the metallic ore and the gangue particles.
  • Froth flotation process :Froth flotation process is based on the wetting characteristic of the ore and the gangue particles with oil and water, respectively.
  • Electromagnetic Separation:Electromagnetic separation is based on the separation of magnetic ores from the non-magnetic impurities by means of electromagnets or magnetic separators.
  • Roasting:It is a process of heating the concentrated ore to a high temperature in excess of air.
  • Smelting:Smelting is further heating of the roasted ore with sand flux and coke in the presence of excess of air in a blast furnace.
  • Bassemerization: Bassemerization is the further heating of the molten matte in a pear shaped bessemer converter.
  • Matte:A mixture of cuprous sulphide alongwith some unreacted ferous sulphide is callled matte. (Cu2S.FeS).
  • Calcination:Calcination is to heat a substance to a high temperature but below the melting point , causing loss of moisture, reduction or oxidation and the decomposition of carbonates and other compounds.
  • Petroleum :Petroleum is a complex mixture of several gaseous, liquid and solid hydrocarbons having water, salts and earth particles with it.
  • Crude Oil:A mixture of naturally occuring hydrocarbons or unrefined petroleum , brownish in colour and is formed by dead remains of plants and animals inside earth.
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