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FIITJEE, NTSE, NATIONAL TALENT SEARCH EXAM, Stage - II (2017), Class X Appeared, CHEMISTRY, SCHOLASTIC APTITUDE TEST (SAT), @FitjeeSM

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CARBON & ITS COMPOUND, Carbon has a unique place in our life. Each living cell, food, wood, paper, petrochemicals, cooking, gas, perfumes etc. are all made of carbon, Carbon is an essential component of all living matters as, proteins, carbohydrates and fats., Bonding in Carbon : A carbon atom has a total of six electrons carbon atom has four valence, electrons. It could gain four electrons to form C+ anion or lose four electrons to fom C" cation. Both, these conditions require large amount of energy. Thus it has a very little tendency to form ionic, compounds. To overcome this problem carbon undergoes bonding by sharing its valence electro, with other carbon atoms or with atoms of other elements. This allows it to be covalently bonded to, one, two, three or four carbon atoms or atoms of other elements or groups of atoms (molecule)., Formation of covalent bond : Covalent bond fommation involves sharing of electrons between, bonding atoms which may be either same or different. The bonding atoms contribute equal number of, electrons (e.g. one electron each or 2 electrons each etc)., Covalency : The number of electrons contributed by an atom for sharing is known as its covalency., Depending upon the number of electrons shared by each atom in bond formation, covalent bond may, be single, double or tripie., Example:, H2 → H(1) = 1, H-H, O2 → O(8) = 2, 6, O = 0, N2 N (7) = 2, 5, N=N, Characteristics of covalent compounds:, (i), These compounds are molecular in nature (i.e. they exist as single molecules) e.g. H2, Cl, NH3,, CH4, SO2 etc., (ii) These are insoluble in water and soluble in benzene, kerosene and petrol etc., (ii) These compounds are poor conductor of electricity., (iv) It is a weak bond due to weak intermolecular forces. Covalent compounds have low melting and, boiling points., Allotropy in Carbon : The property due to which an element exists in two or more forms, which differ, in their physical and some of the chemical properties is known as "Allotropy" and the vanous forms, are called "Allotropes"., ) Allotropes are formed due to the difference either in the number of atoms in the molecules or, arrangement of atoms in the molecules., (i) Carbon exists in two allotropic form (1) crystalline (1) amorphous. The crystalline forms are, diamond and graphite whereas the amorphous forms are coal, charcoal, lamp black etc., (ii) Both diamond and graphite are formed by carbon atom, the difference lies in the manner in, which the carbon atom are bonded to one another., (iv) In diamond each carbon atom is bonded to four other carbon atoms tetrahedrally by covalent, bond. Thus it has a three dimensional network structure., (v) Graphite has a two dimensional sheet structure in which each carbon atom is linked to three, carbon atoms in a hexagonal planar structure., (vi) Diamonds is the hardest substance known while graphite is smooth and slippery., (vii) Graphite is a very good conductor of electricity whereas diamond is a bad conductor of, electricity., FINJEE Ltd., FIT JEE House, 2YA, ralu Sugi, Servaprlya Vihar, New Dethl 110016, Ph 46106000, 26509493, Fas 2551393, ehsite: www.fiitjee.com, FitjeeSM

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Carbon atom is unique amongst all the elements that are found in nature. It can fom long chain, NTSE-Stage-ll-2017-Chemistry-Carbon & Its Compound-58, (Viii) Fullerenes form another class of carbon allotropes. The first one to be identified was C-60, has carbon atoms arranged in the shape of a football. Since this looked like the geodesic de, designed by, the US architect Buckminister Fuller, the molecule was names fullerenes, molecules. The ability of carbon to form a long chain is called catenation. Carbon foms strong bo, because of its small size which enables the nucleus to held on to the shared pairs of electro, strongly. The chains are formed because carbon atoms form tetravalent bonds with other cart, atoms. This structure can be repeated endlessly without disturbing the stability of the bonds and, compounds fomed. The chains can fom branches, and sub-branches. The carbon atoms also fo, rings., Catenation is also present in silicon (Si) with atomic number (Z) equal to 14. Its valence she, electronic configuration (2, 8, 4) is similar to carbon. However, only seven to eight atoms of the, element can be linked by covalent bonds, It is because of smaller bond dissociation energy of Si, bond (200 kJ m) as compared to that of C-C bond. Therefore, the bonds in the silicon atoms an, not as strong as in carbon atoms., In saturated compounds the valencies of all the carbon atoms are satisfied by single bonds between, them. These compounds are very less reactive. e.g. C2H6., C3H8 etc., While in the unsaturated compounds, the valencies of all the carbon atoms are not satisfied by single, bonds, thus in order to satisfy their valencies, they form double or triple bond between the carbon, atoms. They are more reactive than the saturated carbon compounds. e.g. C2H2, C2H4, C3H6 etc., Straight chain compounds : The compounds which contain straight chain of carbon atoms are, called straight chain compounds. e.g. nomal bulane (CH10), normal pentane (CSH12) etc., Branched chain compounds Those compounds, compounds., E.g. iso-butane (C.H10), isopentane (CH, which are branched are called branched chair, eopentane (CsH12) etc., Closed chain compounds or Ring, compounds. E.g. cyclohexane., (C3H6) etc., ompounds : Cyclic compounds are called closed chain or ring, e), cyclopentane (CSH10), cyclobutane (CaHs), cyclopropane, Condensed, formula,, Structural, formula, Common, Name, Bond line, Molecular, Formula, notation,, Representation, CH,, CH., Cyclopropane, HC-, CH2, CH2, H,C, CH,, Cyclopentans, HC-CH,, All those compounds which contain just carbon and hydrogen are called hydrocarbons. Among thes, the saturated hydrocarbons are called alkanes and the unsaturated hydrocarbons containing doub, bonds are called alkenes, while the unsaturated hydrocarbons containing triple bonds are calk, alkynes., The atom or group of atoms which determine the properties of a compound is known as function, group. e.g.-OH (alcohol),, -CHO (aldehyde), A series of compounds in which the same functional group substitutes hydrogen in a carbon chain, called a homologous series. e.g. CH3CI and C2H,CI differ by a-CH2 unit, similarly CHsCOH, CH;OH also differ by a --CH, unit., FITT JEE Z.ed., FIUTJEE House, 29 A, Kalu Saal, Sarvapriya Vihar, New Delht -110016, Ph 46106000, 26559493, Fax 26513942, website:

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NTSE-Stage-ll-2017-Chemistry-Carbon & Its Compound-59, Characteristics of homologous series:, O They can be represented by the same general formula e.g. Alkanes (CHn+2), Alkenes (CHzn)., Alkynes (C,Hz-2) etc., (1) All the members of a homologous series contain the same functional group. e.g. alcohols contain, -OH group; aldehydes contain-CHO group etc., (ii) All the members of a homologous series can be prepared by same general methods of, preparations., (iv) They have similar chemical properties., (v) They show gradation in physical properties like m.p. and b.p. (generally these increase with, increase in, molecular weight), Homologous series, Straight Chain Alkanes, General formula, Example, Functional group, C,H+2 (n more than or equal to 1), CH (n more than or equal to 1), CH (n more than or equal to 2), CH, n 1, Alkyl, Alkenes and Cyclic Alkanes, CH, n 1, CH4, n-24, C,H-2 (n more than or equal to 2) CH2, n=2, C,H OH (n more than or equal to 1) CH,O, n= 1, C,HO2 (n more than or equal to 1) CH,O2, n-1, Alkynes, C-C, Alcohols, C= C, Carboxylic acids, - OH, - COOH, Nomenclature, Chemists developed a set of rules, for naming organic compounds based on their structures which is, known as IUPAC rules, where IUPAC stands for the "International Union of Pure and Applied, Chemistry"., The IUPAC name of an organic compounds consisis of three parts., Prefix-word root-Suffix, Word Root: A word root indicates the nalure of basic carbon skeleton. e.g. a compound containing, four, carbon atom have the name butane, In case a functional group is present,, prefix or as a suffix., While adding the suffix to the wo, carbon chain with an alcohol group would be named as, Propane-'e' = Propan + ol- Propanol., If the carbon chain is unsaturated then the final 'ane' in the name of the carbon chain is substituted by, 'ene' or 'yne' respectively for double and triple bonds., Ns indicated in the name of the compound with either as a, Figees, root the terminal 'e' of carbon chain is removed e.g. a three, Functional group, Еxample, HHH, Functional group, Prefix/Suffix, IUPAC Name, 1. Halogen, Chloro, bromo, lodo -CI,- Br, -1, H-C-C-C- Br, -Bromopropane, H H H, H H, -OH, Н-с-ҫ-он, -ethanol, 2.Alcohol, -ol, H H, CH;CH2CH2CHO, CH;COCH3, -CHO, -Butanal, 3. Aldehyde, -al, -Propanone, -Propanoic acid, -CO, 4. Ketone, -one, CH3CH2COOH, CH3CH2 NH2, CH3COOCH3, CH,-CH CH2, CH; -CH2-C = CH, -COOH, 5. Carboxylic acid, -oic acid, -Amino ethane, -NH2, 6. Amine, Amino, -Methyl ethanoate, -COOR, 7. Ester, oate -, -Propene, 8. Double bond, ene, -Butyne, 9. Triple bond, yne, Ltd., FUTJEE House, 29-A, Kulu Saral, Sarvapriya Vihar, New Delhi -110016, Ph 46106000, 26569493, Fax 26513849, websita: www fitjee.com

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FINJEE Ltd., FITTJEE House, 29-A, Kalu Sarai, Sarvapriya Vihar, New Delhi 110016, Ph 46106000, 26569493, Fax 26513942, NTSE-Stage-ll-2017-Chemistry-Carbon & Its Compound-60, Chemical Properties of Carbon Compounds:, Combustion reaction: Carbon undergo combustion reaction and produce carbon dioxide with, the evolution of heat and light. Most carbon compounds release a large amount of heat and, light on buming., C+ O2 CO2 + heat and light, CH, + O2 → CO2 + H20 + heat and light, CH;CH2OH + O2 → CO2 + H0 + heat and light, (1), Saturated hydrocarbons generally give a clean flame while unsaturated carbon compounds give a, yellow flame with lots of black smoke. Yellow flame signifies incomplete combustion of fuel., All combustion reactions are basically oxidation reactions carried in the presence of air or oxygen. It, is not necessary that reactants may burn during combustion., Combustion of ethyne (C2H) with oxygen is used in gas welding., If the combustion of an organic compound (particularly of hydrocarbons) is properly controlled it may, give useful organic compound., (ii) Addition reaction : Generally alkanes do not undergoes addition reaction. Alkanes are found to be, least reactive unsaturated hydrocarbons, alkenes and alkynes are more reactive. Among alkene and, alkynes, the alkenes are more reactive Unsaturated hydrocarbons undergo addition reaction in, presence of catalysts e.g., H H, R, Ni, R-Ć-C-R, H2, R., This reaction is commonly used in the hydrogenation of vegetable oils., Other examples of addition reactions are:, CH, = CH, Biz/Cc CH, CH,, Fitee SM, CH2 = CH2 + HCI CH3-CH2CI, (i) Substitution reaction : Saturated hydrocarbons give substitution reaction e.g. methane in presence, sunlight undergo chlorination., hu, of, CH4 + Cl2, CH CI + HCI, hu, CH3CI + Clz -, CH2CI2 + HCI, hu, CH,Cl, + Cl2, CHCI, + HCI, hu, CHCI; + Cl2, → CCI4 + HCI, Carbon tetrachlłoride, Substitution reactions by Brz and I2 can also be carried out in similar manner,, Some Important Carbon Compounds, Alcohols: Compounds containing-OH group attached to a carbon atom are known as alcohols. The, general formuia for alcohol is R- OH, where R is an alkyl group and -OH is a functional, group., Example: Ethanol (C2HSOH) commonly known as alcohol., Properties of Ethanol :, Physical properties:, (i) Ethanol is a colourless liquid at room temperature. Its b.p. is 351K. It is neutral to litmus., (i) Ethanol is commonly called alcohol and it is an active ingredient of all alcoholic drinks., (iii) Ethanol is a hypnotic (sleep producer), Chemical properties:, (1) Combustion : Ethanol is highly inflammable liquid and catches fire easily, burns with a blue fname, C2H¢OH + 3O22CO, + 3H,O + heat + light, website: www.ftitjee.com