Bihar Board Class 10 · Science · Matric exam 2027
Chapter 4: Carbon and its Compounds — notes
The chapter’s 8 parts in the book’s order — the first idea of each and the points Medha Ma’am writes on the board — and the summary at the end. The full lesson and a check question for each part are in the app.
1. The Covalent Bond
Okay, so you've already studied ionic compounds.
- • Covalent bond: sharing of an electron pair between two atoms
- • Carbon: atomic number 6, 4 valence electrons
- • C4- or C4+ not easily formed
- • H2: single bond; O2: double bond; N2: triple bond
- • CH4: carbon shares electrons with 4 hydrogen atoms
- • Covalent compounds: low melting/boiling points, poor conductors
2. Allotropes of Carbon
Okay, so, carbon doesn't always look the same.
- • Allotropes: different forms of the same element
- • Diamond: each C bonded to 4 other C atoms, 3-D structure, hardest substance
- • Graphite: each C bonded to 3 other C atoms, hexagonal layers, good conductor
- • Fullerene: C-60, football-shaped, named after Buckminster Fuller
3. Versatile Nature of Carbon: Catenation and Tetravalency
Okay, so carbon forms an enormous number of compounds, about three million of them, more than all other elements combined.
- • Catenation: carbon atoms bond to other carbon atoms (chains, branches, rings)
- • Tetravalency: carbon has valency of 4
- • Saturated compounds: only single bonds between carbon atoms
- • Unsaturated compounds: double or triple bonds between carbon atoms
- • Wohler (1828): prepared urea from ammonium cyanate
4. Chains, Branches, Rings and Isomers
Carbon chains can have many carbon atoms, like methane (1 carbon), ethane (2 carbons), propane (3), butane (4), pentane (5) and hexane (6).
- • Methane CH4, Ethane C2H6, Propane C3H8, Butane C4H10
- • Butane: two structures possible, same formula, different skeleton = structural isomers
- • Cyclohexane C6H12: ring structure
- • Hydrocarbons: compounds of only C and H
- • Alkanes (saturated), Alkenes (double bond, e.g. ethene C2H4), Alkynes (triple bond, e.g. ethyne C2H2)
5. Functional Groups and Homologous Series
Okay, so carbon doesn't bond only with hydrogen.
- • Functional group: atom/group that gives carbon compound its properties
- • Alcohol -OH, Aldehyde, Ketone, Carboxylic acid
- • Homologous series: same functional group, different chain lengths
- • Successive members differ by -CH2- unit
- • Naming: propane - e + one = propanone; propane + ene = propene
6. Chemical Properties: Combustion, Oxidation, Addition, Substitution
Okay, so — let's talk about how carbon compounds react.
- • Combustion: C + O2 -> CO2 + heat and light
- • CH4 + O2 -> CO2 + H2O + heat and light
- • Oxidising agents: alkaline KMnO4, acidified K2Cr2O7 (alcohol to acid)
- • Addition reaction: unsaturated + H2 (catalyst Pd/Ni) -> saturated
- • Substitution reaction: CH4 + Cl2 -> CH3Cl + HCl (sunlight)
7. Ethanol and Ethanoic Acid
Okay, so let's talk about ethanol and ethanoic acid.
- • Ethanol reacts with Na: 2Na + 2CH3CH2OH -> 2CH3CH2O-Na+ + H2
- • Ethanol + conc. H2SO4 at 443K -> ethene + water (dehydration)
- • Ethanoic acid: melting point 290K, called glacial acetic acid
- • Esterification: acid + alcohol -> ester (acid catalyst)
- • Ester + NaOH -> alcohol + salt (saponification)
- • CH3COOH + NaHCO3 -> CH3COONa + H2O + CO2
8. Soaps and Detergents
Okay, so think about oily dirt on clothes.
- • Soap: sodium/potassium salt of long-chain carboxylic acid
- • Micelle: ionic end faces water, carbon chain faces oil droplet
- • Micelle formation helps dissolve dirt in water
- • Hard water + soap -> curdy scum (calcium/magnesium salts)
- • Detergents: ammonium/sulphonate salts, work even in hard water
Summary
Okay, so let's look back at everything we've covered. We started with carbon forming covalent bonds by sharing electrons, since it can't easily form ions. That sharing gives single, double or triple bonds — you saw this in H2, O2, N2 and CH4. Then we looked at carbon's allotropes, diamond and graphite, so different in properties because their atoms are arranged differently, and also fullerenes like C-60. We saw that carbon's versatile nature comes from two things — catenation and tetravalency. These give us saturated and unsaturated compounds, chains, branches, rings, and structural isomers, like the two forms of butane. After that, we learnt how functional groups — alcohol, aldehyde, ketone, carboxylic acid — give carbon compounds their properties. And a homologous series, remember, is just a family of compounds sharing the same functional group, on chains that keep getting longer. Then came the chemical properties — combustion, oxidation, addition and substitution reactions — followed by the specific behaviour of ethanol and ethanoic acid. And finally, soaps and detergents — how they clean oily dirt by forming micelles, and why soap forms scum in hard water while detergents don't. Quite a journey, isn't it? Which of these ideas felt the trickiest to you?
AskMedha · Medha Ma’am — Bihar Board Class 10 Science, Chapter 4. Written from the textbook, checked twice.
Questions parents and students ask
- How do I get the "Carbon and its Compounds" notes as a PDF?
- Press "Save as PDF" — the phone’s print sheet opens; choose "Save as PDF" there. The PDF holds the notes only.
- Where are these notes written from?
- From the chapter’s own textbook text, part by part, in the book’s own terms; a second, independent model then checked every part against the book. The full lesson, a check question for each part and the practice are in the AskMedha app.
The same preparation, with Medha Ma’am — on your phone
Every question of every chapter with its model answer, practice questions in the board’s own shapes, 60 minutes of class a day, written answers marked, a test every Sunday and a WhatsApp report to parents.
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