Atoms, bonds and the periodic table: free 3D labs and a game
Chemistry gets easy when you can see the atom. Build atoms from protons, neutrons and electrons, watch an electron jump from sodium to chlorine, pull a covalent bond apart and turn molecules around in 3D. Everything here is free, forever.
🎮 Step 0: play the periodic table game
Explore all 118 elements, place them in the right box, take a quiz and build atoms. No sign-up needed.
The labs, in the order to do them
Basic concepts
Counting atoms and molecules, and how much reacts with how much.
Mole concept: grams, moles, particles and gas volume · free · Class 11, Unit 1
To understand the mole as a counting unit, and to convert between mass, amount in moles, the number of particles and the volume of a gas at STP.
Stoichiometry: limiting reagent, mass of product and percentage yield · free · Class 11, Unit 1
To use the mole ratio of a balanced equation to find the limiting reagent, the amount of product formed, the excess reactant left and the percentage yield.
Volume strength of hydrogen peroxide: molarity, normality and % w/v · free · Class 11, Unit 1
To understand what the volume strength of hydrogen peroxide means and to convert it to molarity, normality, grams per litre and percentage w/v.
The atom
Protons, neutrons, electrons and the wave nature of the electron.
Build an atom: protons, neutrons and electrons · free · Class 11, Unit 2
To build atoms, isotopes and ions from protons, neutrons and electrons, and to see how the numbers decide the element, the mass number, the charge and the arrangement of electrons in shells.
Electron, proton and neutron: how they were discovered (beams in electric and magnetic fields) · free · Class 11, Unit 2
To see how particles of different charge and mass behave in electric and magnetic fields, and how this led to the discovery of the electron, the proton and the neutron.
Electron clouds: shapes of s, p and d orbitals in 3D · free · Class 11, Unit 2
To see the three-dimensional shapes of s, p and d orbitals, to read their quantum numbers, and to understand what nodes are.
Schrödinger wave equation: wave function, probability and quantised energy · free · Class 11, Unit 2
To see what the Schrödinger equation gives: a wave function ψ for the electron, a probability ψ² of finding it, and energies that are quantised, for an electron in a box and in a hydrogen atom.
Chemical bonds
How atoms join: ionic bonds, covalent bonds and the shapes of molecules.
Ionic bond: how sodium and chlorine make NaCl · free · Class 11, Unit 4
To see how an ionic bond is formed between sodium and chlorine by transfer of an electron, to follow the energy changes, and to understand why ionic compounds form crystals.
Covalent bond: sharing electrons, bond length and bond energy · free · Class 11, Unit 4
To see how a covalent bond forms when two atoms share electron pairs, why there is a best distance (the bond length), and how much energy it takes to break the bond.
Shapes of molecules (VSEPR): CO₂, BF₃, CH₄, NH₃, H₂O, PCl₅, SF₆, XeF₄ · free · Class 11, Unit 4
To see how the shape of a molecule follows from the number of bond pairs and lone pairs around the central atom (VSEPR theory), and how shape decides bond angles, hybridisation and polarity.
Redox and electrochemistry
Oxidation numbers, electron transfer and the Daniell cell.
Oxidation number: rules and the structure method · free · Class 11, Unit 7
To find the oxidation number of an atom in a molecule or ion, first by the algebraic rules and then by the structure (Lewis structure) method, and to see that the two methods agree.
Fractional oxidation number: S₄O₆²⁻, C₃O₂, Fe₃O₄ and Pb₃O₄ · free · Class 11, Unit 7
To understand why the algebraic method sometimes gives a fractional oxidation number, and to find the real whole-number oxidation numbers of the atoms from the structure.
Redox reaction: electron transfer, oxidising and reducing agents · free · Class 11, Unit 7
To see that oxidation and reduction go together as a transfer of electrons, to identify the oxidising and reducing agents with the help of oxidation numbers, and to predict whether a displacement reaction happens.
Electrochemistry: cell potential, Nernst equation, ΔG and equilibrium constant · free · Class 12, Chapter 2
To see how the potential of an electrochemical cell depends on the electrodes (standard potential E°), on the concentrations of the ions (Nernst equation) and on the temperature, and to relate E to ΔG and the…
Daniell cell (galvanic cell): electrons, ions, salt bridge and cell potential over time · free · Class 12, Chapter 2
To see how a Daniell cell produces an electric current from a redox reaction: where the electrons flow, what the salt bridge does, what happens at each electrode and why the cell potential falls with time.
Why start with the atom?
Everything in chemistry comes from the atom. The number of protons decides the element, the electrons in the outer shell decide how it bonds, and the way atoms share or transfer electrons decides the shape and the properties of molecules. These labs follow that story: atom, electrons, orbitals, bonds and shapes.
Next: the full list of Class 11 chemistry practicals and the complete lab catalogue.
Frequently asked questions
Are the atom and bond labs free?
Yes. All of them are free forever. The periodic table game needs no sign-up at all; the 3D labs need a free account so your progress is saved.
In which order should I do the labs?
Start with the periodic table game and the basic concepts (mole, stoichiometry), then build an atom, see how the electron, proton and neutron were discovered and look at the orbitals. After that do the ionic bond, the covalent bond and the shapes of molecules, and finish with redox and the Daniell cell.
Which chapters of NCERT Class 11 Chemistry do they cover?
Some Basic Concepts of Chemistry (Chapter 1), Structure of Atom (Chapter 2), Chemical Bonding and Molecular Structure (Chapter 4), Redox Reactions (Chapter 7) and Electrochemistry (Class 12, Chapter 2), plus the periodic table from Chapter 3.
Can I use them in Hindi?
Yes. The theory, procedure and viva questions of every lab are available in Hindi: switch the language from the header.