Chemistry Class 10 Unit 8 Organic Chemistry Notes (FBISE)

Organic chemistry: study of carbon compounds. Displayed formula: shows every atom and every bond as a line. Condensed (structural) formula: groups atoms, omits some bonds (CH₃CH₂CH₃). Functional group: the atom or group that decides a compound's class and reactions.
IUPAC name = stem (number of carbons) + suffix (class). Stems: meth 1, eth 2, prop 3, but 4, pent 5, hex 6, hept 7, oct 8, non 9, dec 10.
Alkane: -ane, all single C-C bonds, CₙH₂ₙ₊₂. Alkene: -ene, at least one C=C, CₙH₂ₙ. Alkyne: -yne, at least one C≡C, CₙH₂ₙ₋₂. Alcohol: -ol, hydroxyl group -OH. Carboxylic acid: -oic acid, -COOH. Ester: RCOOR′ from an acid and an alcohol.

Methane CH₄; ethane CH₃CH₃; propane CH₃CH₂CH₃; butane CH₃CH₂CH₂CH₃.
Ethene CH₂=CH₂; propene CH₃CH=CH₂; but-1-ene CH₂=CHCH₂CH₃; but-2-ene CH₃CH=CHCH₃. Ethyne HC≡CH; propyne CH₃C≡CH; but-1-yne CH≡CCH₂CH₃; but-2-yne CH₃C≡CCH₃.
Methanol CH₃OH; ethanol CH₃CH₂OH; propan-1-ol CH₃CH₂CH₂OH; propan-2-ol CH₃CH(OH)CH₃; butan-1-ol CH₃CH₂CH₂CH₂OH; butan-2-ol CH₃CH(OH)CH₂CH₃. (Propan-1-ol and propan-2-ol have the same molecular formula C₃H₈O but different structures.)
Methanoic acid HCOOH; ethanoic acid CH₃COOH; propanoic acid CH₃CH₂COOH; butanoic acid CH₃CH₂CH₂COOH. The -COOH carbon is always carbon number 1.
Ester naming: the alkyl group from the alcohol first, then the acid name with -ic acid changed to -ate. CH₃COOCH₃ is methyl ethanoate; CH₃CH₂COOCH₃ is methyl propanoate. Ethanol + propanoic acid gives ethyl propanoate CH₃CH₂COOCH₂CH₃.

Write the carbon chain, number it from the end that gives the smaller number to the functional group or double bond, place the double bond or OH on the numbered carbon, then add hydrogens so each carbon has four bonds, and draw every C-H and O-H bond as a line. For an alcohol draw the O-H bond too.
Example butan-1-ol displayed: H3C-H2C-H2C-H2C-OH written with every bond (four carbons in a row, each with its hydrogens, OH on carbon 1). Example butan-2-ol: the OH sits on the second carbon of the four.

Draw the structural and displayed formula of propan-1-ol (B), butan-1-ol (D), butan-2-ol (M, D). Use the structures above, and show all the bonds in the displayed one.
2025 MCQ: which is a straight-chain hydrocarbon; functional group in carboxylic acids is -COOH.
Name the functional groups of ethanol and ethanal (2025): -OH (hydroxyl) in ethanol; -CHO (aldehyde) in ethanal.

Chemistry Class 10 Unit 8: Organic Chemistry Notes