Summary of carbon and its compounds class 10 cbse
Answers
1. Bonding in Carbon
Carbon form covalent bonds.
Formation of covalent bond : Covalent bond formation involves sharing of electrons between bonding atoms which may be either same or different.
Covalency : The number of electrons contributed by an atom for sharing is known as its covalency.
Characteristics of covalent compounds :
(i) These compounds are molecular in nature (i.e. they exist as single molecules)
(ii) These are insoluble in water and soluble in benzene, kerosene and petrol etc.
(iii) These compounds are poor conductor of electricity.
2. Allotropy in Carbon
The property due to which an element exists in two or more forms, which differ in their physical and some ofthe chemical properties is known as “Allotropy” and the various forms are called “Allotropes”.
Carbon exists in two allotropic form (i) crystalline (ii) amorphous. The crystalline forms are diamond and graphite whereas the amorphous forms are coal, charcoal, lamp black etc.
Fullerenes form another class of carbon allotropes. The first one to be identified was C-60, which has carbon atoms arranged in the shape of a football.
3. Unique Nature of Carbon
Catenation : The property of elements to form long chains or rings by self linking of their own atoms- through covalent bonds is called catenation. The extent of catenation depends upon the strength of the bonds between the atoms involved in catenation.
4. Saturated and Unsaturated Carbon Compounds
In saturated compounds the valencies of all the carbon atoms are satisfied by single bonds between them.
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.
5. Straight chain compounds : The compounds which contain straight chain of carbon atoms e.g. normal butane (C4H10), normal pentane (5H12) etc.
6. Branched chain compounds : Those compounds which are branched.
e.g. iso-butane (C4H10), isopentane (C5H12), neopentane (C5H12) etc.
7. Closed chain compounds or Ring compounds :
Cyclic compounds are called closed chain or ring compounds e.g. cyclohexane (C6H12), cyclopentane (C5H10), cyclobutane (C4H8), cyclopropane (C3H6) etc.
8. Hydrocarbons
All those compounds which contain just carbon and hydrogen are called hydrocarbons.
9. Functional Group
The atom or group of atoms which determine the properties of a compound is known as functional group. e.g. —OH (alcohol), —CHO (aldehyde), > C = C < (alkene), — C C — (alkyne) etc.
10. Homologous Series
A series of compounds in which the same functional group substitutes hydrogen in a carbon chain is called a homologous series.
e.g. CH3C1 and C2H5C1 differ by a —CH2 unit.
11. Nomenclature
Chemists developed a set of rules, for naming organic compounds based on their structures which is known as IUPAC rules.
The IUPAC name of an organic compounds consists of three parts.
Prefix – word root – Suffix
Word Root : A word root indicates the nature of basic carbon skeleton.
In case a functional group is present, it is indicated in the name of the compound with either as a prefix or as a suffix.
While adding the suffix to the word root the terminal ‘e’ of carbon chain is removed If the carbon chain is unsaturated then the final `ane’ in the name of the carbon chain is substituted by ‘en& or yne’ respectively for double and triple bonds.
Explanation:
Ethanol (CH3CH2OH) 156 351
Methane (CH4) 90 111
Allotropes of Carbon
Allotropy: The phenomenon in which the element exists in two or more different physical states with similar chemical properties are called Allotropy.
Carbon has Three Main Allotropes
Diamond: In this, carbon, an atom is bonded to four other atoms of carbon forming three-dimensional structures. It is the hardest substance and an insulator. It is used for drilling rocks and cutting. It is also used for making jewellery.
Graphite: In this, each carbon atom is bonded to three other carbon atoms. It is a good conductor of electricity and used as a lubricant.
Buckminster Fullerene: It is an allotrope of the carbon-containing cluster of 60 carbon atoms joined together to form spherical molecules. It is dark solid at room temperature.
Versatile nature of Carbon, Hydrocarbons, Isomerism, Homologous series, Functional groups, Nomenclature of functional groups.
Versatile Nature of Carbon: The existence of such a large number of organic compounds is due to the following nature of carbon,
Catenation
Tetravalent nature.
(i) Catenation: The self linking property of an element mainly carbon atom through covalent bonds to form long straight, branched and rings of different sizes are called Catenation.
This property is due to
The small size of the carbon atom.
The great strength of the carbon-carbon bond.
Carbon can also form stable multiple bonds (double or triple) with itself and with the atoms of other elements.
Straight Chain
Carbon and its Compounds Class 10 Notes Science Chapter 4 5
Branched Chain
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Rings
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(ii) Tetravalent Nature: Carbon has valency of four. It is capable of bonding with four other atoms of carbon or some other heteroatoms with single covalent bond as well as double or triple bond.
Carbon and its Compounds Class 10 Notes Science Chapter 4 8
Hydrocarbons: Compounds of carbon and hydrogen are known as hydrocarbons.
For example; Methane (CH4), Ethane (C2H6), Ethene (C2H4), Ethyne (C2H2) etc.
Carbon and its Compounds Class 10 Notes Science Chapter 4 9
Saturated Hydrocarbon (Alkanes): General formula is CnH2n+2.
n = number of carbon atoms.
In this, the carbon atoms are connected by only a single bond.
For example; Methane (CH4), Ethane (C2H6) etc.
Carbon and its Compounds Class 10 Notes Science Chapter 4 10
Unsaturated Hydrocarbons
Alkenes: General formula is CnH2n, where n = number of carbon atoms.
In this, the two carbon atoms are connected by double bond.
Carbon and its Compounds Class 10 Notes Science Chapter 4 11
Alkynes: General formula is CnH2n-2, where n = number of carbon atoms. In this, the two carbon atoms are connected by triple bond.
Carbon and its Compounds Class 10 Notes Science Chapter 4 12
Electron Dot Structure of Hydrocarbons
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Isomerism: Compounds having the same molecular formula but different structural formula and properties are known as Isomers and this phenomenon is known as Isomerism.
Structural Isomerism: Compounds having the same molecular formula but different structures are called Structural isomers. Example: Isomers of butane (C4H10)
Carbon and its Compounds Class 10 Notes Science Chapter 4 14
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Homologous Series: Series of organic compounds having the same functional group and chemical properties and successive members differ by a CH2 unit or 14 mass units are known as Homologous series.
Homologous series of Alkanes, Alkenes and Alkynes
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Characteristic of Homologous Series
The successive members in homologous series differ by CH2 unit or 14 mass unit.
Members of given homologous series have the same functional group.
All the members of homologous series shows similar chemical properties.
Functional Group: An atom or group of atoms present in a molecule which largely determines its chemical properties are called Functional Group