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Chemistry notes for Class 11 and 12
Physical, organic and inorganic, written from the NCERT outward. Structure first, then the exam patterns that keep coming back.
- Class 11 · Practice set
Stoichiometry and Concentration
Stoichiometry questions in JEE are rarely about the mole itself. They are about applications: back titration, double titration with an indicator change, the strength of oleum, the volume strength of hydrogen peroxide, and eudiometry. This set works through twenty-four such problems, with the full solution shown for each.
- Class 11 · Chapter notes
Chemical Bonding and Molecular Structure
Atoms bond to reach a lower energy, not to obey a rule. From there everything follows: ionic bonding when one atom takes electrons outright, covalent when they are shared, VSEPR to predict the shape from electron pairs, hybridisation to explain it, and molecular orbital theory for the cases where the simpler pictures fail.
- Class 11 · Chapter notes
Classification of Elements and Periodicity
The periodic table is a map, not a list to memorise. Four trends run through all of it, and all four come from one idea: how hard the nucleus pulls on the outermost electron. Nuclear charge rises across a period while shielding stays roughly constant, so the pull tightens; down a group a new shell wins, and the pull weakens.
- Class 11 · Chapter notes
Structure of the Atom
The atom was taken apart and rebuilt over about thirty years. Cathode rays gave the electron, scattering gave the nucleus, and the hydrogen spectrum showed energy comes in steps. Bohr fixed the steps by decree; de Broglie and Heisenberg explained why they exist, and the quantum model replaced orbits with orbitals described by four quantum numbers.
- Class 12 · Chapter notes
Biomolecules
The Class 12 chemistry treatment of biomolecules is about structure and tests rather than function. Carbohydrates are classified by what they hydrolyse into and identified by reducing tests, proteins by their linkage and levels of structure, and nucleic acids by their three components. Most marks come from tables you can learn directly.
- Class 12 · Chapter notes
Aldehydes, Ketones and Carboxylic Acids
One polar bond explains the whole chapter. Oxygen has already pulled the pi cloud away from the carbonyl carbon, so that carbon is electron poor and nucleophiles attack it — the opposite of an alkene. Reactivity falls as you add alkyl groups and bulk, which is why aldehydes react faster than ketones, and whether a carbonyl has an alpha hydrogen decides between aldol and Cannizzaro.
- Class 11 · Chapter notes
Inductive and Mesomeric Effects
The sign is written from the molecule's point of view, never as a charge: minus means the rest of the molecule loses electron density, plus means it gains. The letter says which wire the effect travels on — I along sigma bonds, fading to nothing after about three carbons, and M through the pi system, which does not fade because the electrons are genuinely delocalised.
- Class 12 · Chapter notes
Reagents and Their Roles
Students do not confuse reagents, they skip conditions. The same KOH gives an alkene in alcohol and an alcohol in water; the same sulphuric acid removes water when concentrated and adds it when dilute; the same HBr follows Markovnikov without peroxide and reverses with it. Read the word before the formula, because that word is usually the answer.
- Class 11 · Chapter notes
Isomerism
Isomers share a molecular formula. One question sorts them: does the connectivity differ, or only the arrangement in space? Different connectivity is structural isomerism, which covers chain, position, functional and metamerism. The same connectivity is stereoisomerism, which splits into geometrical, described by cis/trans and the E/Z system, and optical, where chirality, meso forms and R/S configuration decide what you are looking at.
Read it, then play it.
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