LearnChem

The course map

Thirty-one modules in six parts, from what stuff is made of to how anyone knows. Each one is a question.

§1

What this course is

LearnChem is a chemistry course for students in classes IX to XII — and for anyone who was taught chemistry as a list of things to remember and would rather see it as one connected argument. It runs from the first question, why a furnace cannot make gold, to the last, how anyone knows what a molecule looks like. On the way it covers the ground the board syllabus covers: atoms and the periodic table, bonding and the structure of solids, heat, entropy and free energy, gases, rates and equilibrium, acids, solutions, rusting and metal extraction, and then organic chemistry from carbon’s four bonds through to polymers and spectroscopy.

Take one module at a time, in order, and don’t read it like a chapter. Every module is built around benches you can move — sliders, dials, panels that recalculate — and they are there to be guessed at before they are touched. Predict first, then move the slider, then read the explanation. That order is what makes an idea stay. Each module closes with one sentence worth keeping. By the end you should be able to meet an unfamiliar reaction and ask the three questions that matter — will it go, how fast, and what will it give — and answer them from a handful of ideas rather than a memorised list.

What is unusual about this course is that it never asks you to take its word for anything. Numbers on these pages are computed live from cited constants or quoted from a named source, and where the sources disagree — or where a textbook rule simply fails against the measured data — the page says so instead of tidying it away. A student finishing this is ready for the board exams, but has also practised the thing exams cannot test: predicting before being told, checking a claim against evidence, and telling the difference between an explanation and a rule you happened to remember.

§2

All thirty-one, at a glance

The same modules with the descriptions stripped out, for when you know what you are looking for.

Part 0 · Orientation

01Why can’t we just make gold?

Part I · What is stuff made of?

02What is a flame? 03How do you count something you can’t see? 04How do we know atoms have parts? 05Why is the periodic table that shape?

Part II · Why do atoms stick together?

06What holds atoms together, and what does a bond cost? 07Why do molecules have shapes? 08Why is water so strange? 09Why is metal shiny, salt brittle and diamond hard? 10Why does each family of elements behave the way it does? 11Why are transition metals colourful, and such good catalysts?

Part III · Why do some things react and others just sit there?

12Where does the heat of a reaction come from? 13Why does anything mix, and never unmix? 14What decides whether a reaction happens at all? 15What is a gas actually doing? 16Why do reactions need a push?

Part IV · What makes a reaction go further, or faster?

17Why do reactions stop before they finish? 18What happens when you disturb a balance? 19What makes something an acid? 20Why does anything dissolve? 21Why do some metals rust and others don’t? 22How do you get a metal out of a rock?

Part V · Why that product and not another?

23Why does carbon make so many things? 24Why is benzene different? 25What actually moves when a reaction happens? 26Why this product and not the other one? 27What does an oxygen atom do to a carbon chain? 28Why is the carbon next to an oxygen the one that gets attacked? 29What do the nitrogen groups do, and why does life use them? 30How do small molecules become big ones? 31How does anyone know what a molecule looks like?

§3

The map

Six parts, each one a larger question that its modules answer between them.

Part 0

Orientation

01Why can’t we just make gold?Alchemists heated metals for a thousand years and never made gold. You find out why: chemistry moves electrons, and the nucleus — the thing that decides which element you have — is out of its reach.

Part I

What is stuff made of?

02What is a flame?A candle is cut open and watched in stages, the way Faraday did it. A flame turns out to be a reaction you can see, and air is one of the ingredients rather than the background. 03How do you count something you can’t see?A burnt match weighs less; burnt steel wool weighs more. Atoms cannot be counted, so they are weighed instead — and that is where the mole comes from. 04How do we know atoms have parts?Atoms were opened up without anyone ever seeing one, by watching things bounce off foil and glow inside tubes. You come out with a nucleus, energy levels that come in steps, and electrons that only have likely places to be. 05Why is the periodic table that shape?The energy needed to pull an electron off an atom climbs in steps, not smoothly. Those steps are the shells — and the shells are the entire reason the table has the shape it has.

Part II

Why do atoms stick together?

06What holds atoms together, and what does a bond cost?Two atoms are brought closer and their energy drops into a valley. That is all a bond is — two atoms sitting lower than they stood apart — and the same valley explains why some bonds share electrons while others hand them over. 07Why do molecules have shapes?Four balloons tied at the neck push each other into a fixed arrangement, and electron pairs do exactly the same. Shape follows from the pushing — and shape is what your tongue and your body actually recognise. 08Why is water so strange?A molecule this small should boil at about −90 °C. It boils at 100 °C because every water molecule holds four hands with its neighbours, and letting go of them takes heat. 09Why is metal shiny, salt brittle and diamond hard?Three solids with no molecules in them at all: a sea of electrons, a checkerboard of charges, and one endless bonded network. Each kind of glue leaves its own fingerprint — the shine, the clean split, the hardness. 10Why does each family of elements behave the way it does?A column of the table is a family, and two dials — size and pull — set how each member behaves. You use them to predict a group’s behaviour, and then to explain the member who doesn’t fit. 11Why are transition metals colourful, and such good catalysts?Sitting in a cage of other atoms splits the d shell, and the gap swallows a slice of the white light passing through. The same part-filled shell lets these metals change their charge cheaply, which is what makes them catalysts.

Part III

Why do some things react and others just sit there?

12Where does the heat of a reaction come from?A flame is sealed inside a can of water so the heat can be caught and counted. It turns out to be the difference between the bonds broken and the bonds made, and nothing else. 13Why does anything mix, and never unmix?A shuffled deck never shuffles itself back, and no law forbids it. The reverse is simply outnumbered — and counting arrangements is enough to say which way everything goes. 14What decides whether a reaction happens at all?Two things are weighed against each other: the heat moved, and the freedom gained. Together they set the direction, and they explain why some reactions only start once you heat them. 15What is a gas actually doing?A gas is mostly empty space with particles crossing it, and pressure is just those particles hitting the wall. One temperature holds a whole spread of speeds — and the fastest few explain how wet clothes dry on a cold day. 16Why do reactions need a push?There is a hill between the two valleys, because old bonds have to break before better ones can form. Only the fastest molecules get over it, which is why heating speeds a reaction up and what a catalyst lowers.

Part IV

What makes a reaction go further, or faster?

17Why do reactions stop before they finish?A sealed bottle of soda never goes flat, though nothing in it has run out. The reverse reaction has caught up with the forward one, and a single number fixes where the traffic settles. 18What happens when you disturb a balance?Thin mountain air pushes on your own blood chemistry, and the balance shifts. Each push is priced by how far the mixture now sits from balance — which is where Le Chatelier’s rule comes from, rather than being handed to you as a slogan. 19What makes something an acid?An eggshell goes soft in vinegar because something is handing protons over. Strength and concentration turn out to be two separate dials, and pH is built up from scratch as a count of tens. 20Why does anything dissolve?Borewell water that will not lather, and a sachet of rehydration salts that disappears in a glass. The crystal grips its ions, water pulls at them, and which one wins is what decides whether something dissolves. 21Why do some metals rust and others don’t?An iron grille and an aluminium frame on the same Chennai balcony, in the same salty air, forty years apart in how long they last. Iron gives its electrons to oxygen and water has to be present — and a wire can carry those electrons the long way round instead. 22How do you get a metal out of a rock?Stone, Bronze and Iron arrived in the order set by how tightly each ore holds its metal. A metal in its ore has already given its electrons away, so smelting is paying them back — with carbon, with electricity, or with another metal.

Part V

Why that product and not another?

23Why does carbon make so many things?Silicon also makes four bonds and gets nowhere near as far. Carbon’s bonds to itself hold their value against oxygen, so chains, rings and mirror-image twins carry on without end. 24Why is benzene different?Bromine adds straight onto an ordinary double bond in the dark, and benzene sits there until a catalyst arrives. Six electrons shared right round the ring are worth a measured 150 kJ per mole, and that is what an addition would cost. 25What actually moves when a reaction happens?The curly arrow in every textbook is a claim, not a decoration: one pair of electrons moving into a space that was empty. Follow it and you can say which carbon gets attacked, from which side, and why. 26Why this product and not the other one?Two roads leave the same flask, and the rule for which one you end up on is short. The fastest product wins — unless it can go back, and then waiting gives you the most stable one instead. 27What does an oxygen atom do to a carbon chain?Ethanol boils at 78 °C; the same atoms rearranged as an ether boil at −25 °C. An oxygen can only give up a hydrogen it actually has, and only as easily as the leftover charge can spread out. 28Why is the carbon next to an oxygen the one that gets attacked?Wine turns to vinegar only if the bottle is left open. A carbon is attacked when its neighbour will take the electrons and nothing is in the way — two conditions, and neither outranks the other. 29What do the nitrogen groups do, and why does life use them?The smell at a swimming pool is not chlorine; it is what the chlorine made of the nitrogen the swimmers brought in. A nitrogen’s lone pair can be spent only once, and where it went decides the rest — right down to which DNA base pairs with which. 30How do small molecules become big ones?One reaction repeated makes a chain, and the very same ethene gives either a stiff bottle or a limp film. Soap is the opposite case — big with nothing joined at all, held in shape only by the water around it. 31How does anyone know what a molecule looks like?Nobody has ever looked at a molecule. Every method measures something else — a mass, a wobble, a pattern of spots — and reasons its way back to a structure.

§4

Where your syllabus sits

If you arrived asking “where is chapter 6?”, this is the table for you. Every chemistry unit of the CBSE syllabus for classes IX to XII, checked against the board’s own curriculum pages for 2026–27, and the module or modules that carry it. Numbers in the last column are module numbers, and they are links.

This course is not organised as a syllabus, so a chapter is rarely one module. A board unit usually lands in two or three, and a module usually serves more than one class.

Class IX — Science

Unit II — Matter: Its Nature and Behaviour · 25 marks

Chapter	In this course
5. Exploring Mixtures and their SeparationPartial. This course explains why a thing dissolves and why a mixture never unmixes itself. It does not teach the separation techniques — distillation, chromatography, centrifuging — as bench procedures.	20, 13 also 08, 03
8. Journey Inside the Atom	04 also 05
9. Atomic Foundations of Matter	03 also 01, 06

Class IX moved to the new NCERT “Exploration” book — thirteen chapters, under NCF-SE 2023. The old titles “Matter in Our Surroundings” and “Is Matter Around Us Pure” are gone. Three of the thirteen chapters are chemistry: 5, 8 and 9.

Class X — Science

Unit I — Chemical Substances: Nature and Behaviour · 25 marks

Chapter	In this course
1. Chemical Reactions and Equations	03, 12, 21 also 13
2. Periodic Classification of ElementsIn the syllabus, but not assessed in the year-end board examination.	05, 10
3. Acids, Bases and Salts	19 also 20
4. Metals and Non-metals	09, 10, 21, 22 also 06
5. Carbon and its Compounds	23, 27, 28, 30 also 26

Periodic Classification of Elements is in the class X syllabus for 2026–27, but the board says it will not be assessed in the year-end examination — it is carried through classwork instead. This course teaches it in full anyway, at modules 05 and 10.

Class XI — Chemistry

Unit	Marks	In this course
1. Some Basic Concepts of Chemistry	7	03 also 01
2. Structure of Atom	9	04 also 05
3. Classification of Elements and Periodicity in Properties	6	05, 10
4. Chemical Bonding and Molecular Structure	7	06, 07 also 08, 09, 24
5. Chemical Thermodynamics	9	12, 13, 14
6. Equilibrium	7	17, 18, 19, 20
7. Redox Reactions	4	21 also 28
8. Organic Chemistry: Some Basic Principles and Techniques	11	23, 25 also 31
9. Hydrocarbons	10	23, 24, 26

Nine units, 70 theory marks. States of Matter, Hydrogen, s-Block, p-Block and Environmental Chemistry are no longer separate units.

Class XII — Chemistry

Unit	Marks	In this course
1. Solutions	7	20 also 08
2. Electrochemistry	9	21
3. Chemical Kinetics	7	16 also 15
4. d- and f-Block Elements	7	11 also 10
5. Coordination Compounds	7	11
6. Haloalkanes and Haloarenes	6	25, 26
7. Alcohols, Phenols and Ethers	6	27
8. Aldehydes, Ketones and Carboxylic Acids	8	28 also 25
9. Amines	6	29
10. Biomolecules	7	29, 30

Ten units, 70 theory marks. Solid State, Solutions' colligative depth aside, Surface Chemistry, General Principles and Processes of Isolation of Elements, the p-Block Elements, Polymers and Chemistry in Everyday Life are no longer units.

What the comparison says

27 of the 27 board units land in at least one module, and one of those is partial. Two modules carry no board unit at all: 01 orients, and 02 is Faraday’s candle — the course’s method in miniature.

The course also teaches a fair amount the board dropped in the 2023 rationalisation and has not brought back. That is deliberate — this is an argument, not a syllabus — but it should be said plainly, so that nobody mistakes the extra for exam coverage:

Solid State (class 12) — 09
s-Block, p-Block, Hydrogen (class 11 and 12) — 10
States of Matter (class 11) — 15
General Principles and Processes of Isolation of Elements (class 12) — 22
Polymers (class 12) — 30
Surface Chemistry (class 12) — 11, 16
never in CBSE — 31
Chemistry in Everyday Life (class 12) — the D family throughout

Two things this table does not claim. It is built from the board’s curriculum pages read as text, not from the printed NCERT books, and fine-grained deletions inside a surviving unit — which derivations, which numericals — are reported inconsistently by every source and are not recorded here. Other boards — the state boards, ICSE, IB — are not covered.