Atomic Structure · Chemistry

Atomic Structure Simulation Lab

Thirty-one experiments covering the whole chapter, in the order it is taught for JEE Main and Advanced: Thomson's atom and why it cannot turn an α-particle back, Rutherford's gold foil with real hyperbolic paths, the cathode-ray tube and Thomson's e/m, canal rays, why each model fails; c = νλ, the electromagnetic spectrum, Planck's quanta and photon energies; the photoelectric effect with threshold, work function, stopping potential and Einstein's equation; Bohr's postulates, radius–energy–speed, the hydrogen spectrum, emission and absorption, the five series and any transition's wavelength; de Broglie waves, electron diffraction and 2πr = nλ; and orbitals drawn from hydrogen's real wavefunctions — orbit vs orbital, the four quantum numbers, counting electrons, s, p and d shapes, nodal planes, radial and angular nodes and the radial probability curve.

Interactive virtual lab · no download · works on phones and laptops

Chapter: Structure of Atom
For: Class 11 · 12 · JEE · NEET
Time: ~45 min

Atomic Structure Lab is a Pro simulation

Pro opens all 131 virtual labs — 519 simulations with guides and quizzes.

How to use it

1Pick a module from the list (31, in six groups); set your level at the top right for more controls.
2Change the sliders, choices and toggles; press play where a module has a clock.
3Use Predict before you look, then Derive, Questions, Practise (fresh numericals each time) and Compare.

What to notice

Thomson's spread-out charge can deflect an α-particle by only about 0.01°; Rutherford's nucleus can turn it right round.
One photon frees one electron: K_max = hν − φ depends on the colour of the light, the current on its brightness.
In Bohr's atom r = 0.529 n²/Z Å, v = 2.18 × 10⁶ Z/n m/s and E = −13.6 Z²/n² eV; every spectral line is a jump between two levels.
λ = h/mv: a whole number of wavelengths round an orbit is Bohr's mvr = nh/2π.
An orbital has n − l − 1 radial nodes and l angular nodes; the radial probability, not ψ², peaks at a₀ for 1s.

For teachers

A ready-made teaching kit comes with this lab

Lesson plan
41 min, 4 steps
Ask the class
5 questions with answers
Quick quiz
7 questions, printable
Key formulas
8 formulas

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About the Atomic Structure Lab simulation

Structure of Atom is the first chapter of Class 11 chemistry and one of the most numerical in JEE and NEET. This lab puts the whole of it on one page, in the order it is taught: fire α-particles through Thomson's plum-pudding atom and through Rutherford's nucleus, balance a cathode-ray beam between electric and magnetic fields to find e/m, bend canal rays of six gases, and watch a classical electron spiral into its nucleus in 10⁻¹¹ s.

Then the quantum half: c = νλ and the electromagnetic spectrum, Planck's quanta, the photoelectric effect with real work functions and stopping potentials, Bohr's orbits with their radius, speed and energy for H, He⁺, Li²⁺ and Be³⁺, the hydrogen spectrum and its five series, de Broglie waves and electron diffraction, and hydrogen's orbitals drawn from their actual wavefunctions — shapes of s, p and d orbitals, nodal planes, radial nodes and the radial probability curve.

Each of the thirty-one modules has a prediction question, a derivation, concept questions with hints (single, multiple-correct, assertion–reason, numeric and explain-in-words) and fresh practice numericals every time you ask.

Also covers: structure of atom, atomic structure, thomson model, plum pudding model, rutherford model, gold foil experiment, alpha particle scattering, distance of closest approach, cathode ray experiment, e/m of electron, anode rays, canal rays, limitations of rutherford model, electromagnetic radiation, frequency wavelength, c = νλ, wavenumber, electromagnetic spectrum, planck's quantum theory, energy of photon, photoelectric effect, threshold frequency, work function, stopping potential, einstein photoelectric equation, bohr model, bohr's postulates, radius of bohr orbit, energy of electron in nth orbit, velocity of electron, hydrogen spectrum, emission and absorption spectrum, lyman balmer paschen brackett pfund, rydberg formula, number of spectral lines, de broglie wavelength, dual nature of matter, davisson germer, 2πr = nλ, orbit vs orbital, quantum numbers, shapes of orbitals, s p d orbitals, px py pz, nodal plane, radial nodes, angular nodes, radial probability distribution.

Frequently asked questions

Why did Rutherford's experiment rule out Thomson's model?

In Thomson's atom the positive charge is spread through the whole atom, so its electric field is weak everywhere: the largest deflection of a 5 MeV α-particle by a gold atom is about 0.01°. Geiger and Marsden saw about 1 in 8000 bounce back, which needs the positive charge packed into a tiny nucleus.

Why does brighter light not increase the kinetic energy of photoelectrons?

Each electron is freed by one photon, and a photon's energy hν depends only on the light's frequency. Brighter light means more photons, so more electrons (a larger current), but each still gets hν − φ at most.

How many spectral lines can hydrogen atoms excited to the n-th level emit?

A sample can emit n(n − 1)/2 different lines — one for each pair of levels. A single atom falling from n can emit at most n − 1 photons on its way down.

What is the difference between an orbit and an orbital?

An orbit is Bohr's definite circular path, labelled by n. An orbital is a wavefunction ψ (labelled by n, l and mₗ) whose square gives the probability of finding the electron at each point; it has a shape and holds at most two electrons.

How do I count radial and angular nodes?

Angular nodes = l (planes, except the two cones of dz²); radial nodes = n − l − 1 (spheres); total = n − 1. For example 3p has 1 radial and 1 angular node.