Carbon and its compounds quick revision Class 10 Science is an important topic for students preparing for board exam. This chapter explains the versatile nature of carbon, covalent bonding, allotropes, homologous series, functional groups and important organic compounds like ethanol, ethanoic acid.
This quickrevision notes based on the NCERT Science Class 10 syllabus followed by RBSE help students revise key concepts, reactions and definition in a short time.
This is useful for last minute preparation.After readingthese notes, you can solve questions of the chapter and practice with MCQs forbetter understanding.
Importance of Carbon
- Carbon is present in all living organisms and forms the basis of life.
- It is found in earth’s crust as carbonates, coal and petroleum.
- It is found in atmosphere as carbon dioxide.
- Food, clothes, medicines, fuels, plastics and paper are made of carbon compounds.
- Carbon forms million of compounds due to its unique properties.
Bonding in Carbon
Atomic number – 6
Valency – 4(tetravalent)
Electronic configuration – 1s2 2s2 2p2
Carbon shareselectrons to form covalent bonds with carbon atoms and other atoms.
Properties of Covalent Compounds
i. These compounds have low melting and boiling points
ii. They are found in gaseous and liquid states mostly.
iiiThey are poor conductors of electricity.
Exception: Graphite (allotrope of carbon) is conductor of electricity.
Examples: CH4,CH3CH2OH, CHCl3 etc.
Carbon exists indifferent structural forms.
(i) Diamond
- Eachcarbon bonded to 4 carbon atoms.
- It has rigid 3D structure.
- It is the hardest natural substance.
- It has high melting point.
- It is nonconductor of electricity.
(ii) Graphite
Each carbon bonded to 3 carbon atoms.
It has hexagonal layered structure
It has free electrons so conducts electricity.
It is soft and slippery due to layered slide.
(iii) Fullerene
Buckminsterfullerene is C-60 a well-known allotrope of carbon.
It contains 60 carbon atoms.
It has football-like structure so it is called bucky ball.
Versatile Nature of Carbon
Carbon makes large number of compounds due to following properties:
Catenation
The ability to form a long chain, branches and rings with other carbon atoms.
C – C bonds are strong and stable.
Tetravalency
Each carbon atoms can bonds with four atoms.
Saturated and Unsaturated Hydrocarbons
Hydrocarbons are compounds that have mainly carbon, hydrogen and other elements.
Saturated hydrocarbon
- These hydrocarbons have single bond between carbon atoms.
- They are less reactive.
- They burn with blue flame.
- Examples: alkanes (methane, ethane)
Unsaturated hydrocarbons
- These hydrocarbons have double and triple bonds between carbon atoms.
- They are more reactive.
- They burn with yellow sooty flame.
- Examples: Alkenes and alkynes
Chains, Branches, Rings and Isomerism
Carbon atoms can join with each other in different ways because of catenation. Due to these compounds have straight chain, branched chain and ring structures.
Straight chain compounds (Open chain)
Carbon atoms are connected one after another in a single line.
Examples: methane, ethane, propane
CH3 – CH3 , CH2 = CH2
This is called a normal (n) structure.
Branched chain compounds
These compounds have a side carbon branch attached to the main chain.
Example: Butane
Butane can be arranged in two different ways
n- butane and iso
butane (2-methyl propane)
(n-butane) (iso butane)
Bothe have the same molecular formula but different structures.
Ring Structured Compounds (Cyclic)
Carbon atoms join to form a closed ring, these are called cyclic compounds.
Examples: cyclohexane – it has six carbon atoms forming a ring with single bonds.
Benzene
Benzene has 6 carbon atoms.
It has ring structure.
Six carbon atoms form a ring with alternating double bonds.
It is called aromatic compounds (have a particular smell)
Isomerism
The compounds that have same molecular formula but different structure. These are called isomers.
Example: Butane has two isomeric structures – (i) n-butane (ii) isobutane
These isomers have different physical properties
Functional Groups
The atoms other than carbon and hydrogen is present in carbon compounds are called heteroatoms.
When a heteroatom is attached to a carbon chain, it forms a functional group.
A functional group is the active part of an organic molecule that decides its chemical properties and reactions.
Homologous Series
- It is the series of compounds with same functional group.
- Successive members of series differ by -CH2 unit.
- Each member of homologous series show similar chemical properties.
Example: Alcohol Series – CH3OH, C2H5OH , C3H7OH
General Formula of Hydrocarbons
Alkanes – CnH2n+2
Alkene – CnH2n
Alkynes – CnH2n -2
Nomenclature of Carbon Compounds (Hydrocarbons)
Naming of carbon compounds in a homologous series is based on:
The basic carbon chain name
Add a prefix or suffix to show the functional group
Steps to Name a Carbon Compound
(i) Count the number of carbon atoms in the longest chain
|
No. of carbon atoms |
prefix |
|
1 |
Meth |
|
2 |
Eth |
|
3 |
Prop |
|
4 |
But |
(ii) Identify the functional group (if present): This is added as prefix or suffix to the
base formula
|
Functional group |
Prefix /suffix |
|
Halo group |
Chloro,bromo (prefix) |
|
Alcohol |
Ol (suffix) |
|
Aldehyde |
Al (suffix) |
|
Ketone |
One (suffix ) |
|
Carboxylic acid |
Oic acid (suffix) |
(iii) Rule for adding suffix: if the suffix of the functional group starts with a vowel, then remove the final ‘e’ from the base name and add suffix.
Chemical Properties of Carbon Compounds
1. Combustion
·Carbon compounds burn in oxygen to produce carbon dioxide, water and heat.
CH4 + O2 →CO2 + H2O +heat
·Saturated hydrocarbons burn with blue flame.
·Unsaturated hydrocarbons burn with yellow sooty flame.
·Coal and petroleum release pollutants like SO2. NO2
2. Oxidation
·Ethanol
is converted to ethanoic acid when heated in the presence of alkaline KMnO4 / acidic K2Cr2O7.
·Substances that add oxygen to other substances are called oxidizing agents.
3. Addition Reaction
·Unsaturated hydrocarbons undergo this reaction.
·Hydrogen is added to unsaturated hydrocarbons in the presence of catalyst.
·The reaction is used in the hydrogenation of vegetable oil in the presence of
nickel catalyst for making vegetable ghee.
4. Substitution Reaction
·Saturated hydrocarbons undergo this reaction.
·In the presence of sunlight, chlorine displace hydrogen one by one.
Important Carbon Compounds
(i) Ethanol
(ii) Ethanoic acid
(i) Ethanol (Ethyl alcohol)
Formula: C2H5OH
Uses: used as solvent, in medicines, alcoholic drinks
Chemical reaction of ethanol
i. Reaction with sodium
2Na + 2CH3CH2OH → 2CH3CH2O–Na+ + H2
ii. Dehydrationof ethanol
(ii) Ethanoic acid
Formula – CH3COOH
Properties
· It is weak acid.
· It freezes in winter so it is called glacial acid.
· Its 5-8% solution called vinegar.
Chemical reaction of ethanoic acid
i. Esterification: ethanoic acid reacts with ethanol in the presence of acid to give an ester.
ii. Reaction with base
NaOH + CH3COOH → CH3COONa + H2O
iii. Reactions with sodium carbonate and sodium hydrogen carbonate
CH3COOH + Na2CO3 → 2CH3COONa + H2O +CO2
CH3COOH + NaHCO3 → CH3COONa + H2O +CO2
Soap and Detergents
Soap: These are sodium or potassium salts of long chain carboxylic acids. Soap molecule has water loving end called hydrophilic end and oil loving end called hydrophobic end.
Detergent: These are ammonium or sulphonate salts of carboxylic acids. They work effectively with hard water.
Micelle Formation
A cluster of molecules in which the hydrophobic tails are in the interior of the cluster and the ionic ends are on the surface of the cluster, this formation is called a micelle. This removes dirt during washing.
Conclusion
This quick revision notes of carbon and its compounds is useful of RBSE Class 10 students because it is designed for quick revision and based on NCERT Science text books and
syllabus.
Related Topics
1. Chemical reactions and Equations Quick Revision Notes
2. Acids, Bases and Salts Quick Revision Notes
3. Metals and Non-metals Quick Revision Notes
Frequently Asked Questions
Q1. Why is carbon able to form a large number of compounds?
Answer
Carbon has two properties – catenation and tetravalency.so carbon form long chains, branches and rings and stable covalent bonds.
Q2. What is isomerism?
Answer
Isomerism is a phenomenon where compounds have eh same molecular formula but different structures.
Q3. What is the role of a functional group in a carbon compound?
Answer
A functional group is the active part of the molecule that determines its chemical properties, reactions and naming.
Q4. Why does graphite conduct electricity but diamond does not?
Answer
Graphite has one free electron, so it conducts electricity while diamond has four valence electrons are bonded so it does not conduct electricity.
Q5. What is micelle?
Answer
Micelle is a cluster of soap molecules where hydrophobic end trap dirt and hydrophilic head remain outside in water.