Atomic Structure
World A — Chemistry Foundations
R02.01 Thomson Model
- The "Plum Pudding" concept.
- Positively charged spherical mass.
- Embedded negative electrons.
R02.02 Rutherford Model
- Alpha particle scattering experiment.
- Discovery of the dense nucleus.
- Atom is mostly empty space.
R02.03 Bohr Model
- Quantized stationary circular orbits.
- Energy levels (K, L, M, N).
- Photon emission during electron jumps.
R02.04 Dual Nature of Matter
- De Broglie wavelength ($\lambda = h/mv$).
- Matter exhibits wave-particle duality.
- Foundational for quantum mechanics.
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R02.05 Uncertainty Principle
- Heisenberg's limitation ($\Delta x \cdot \Delta p \ge h/4\pi$).
- Exact position & momentum cannot be known simultaneously.
- End of definite trajectories.
R02.06 Quantum Mechanical Model
- Schrödinger wave equation.
- Electron probability clouds.
- Concept of the atomic orbital.
n3
l1
m-1
s+½
R02.07 Quantum Numbers
- Principal (n): Shell size/energy.
- Azimuthal (l): Subshell shape.
- Magnetic (m): Orbital orientation.
- Spin (s): Electron spin direction.
R02.08 Orbital Shapes
- s-orbital: Spherically symmetrical.
- p-orbital: Dumbbell shaped (x, y, z axes).
- d and f orbitals: Complex geometries.
R02.09 Aufbau Principle
- Electrons fill lower energy levels first.
- Follows the (n + l) rule sequence.
- Determines ground state configuration.
R02.10 Pauli & Hund
- Pauli: Max 2 electrons per orbital, opposite spins.
- Hund's Rule: Maximize parallel spins in degenerate orbitals.
R02.11 Atomic Spectra
- Line emission and absorption spectra.
- Unique spectral fingerprints for elements.
- Hydrogen series (Lyman, Balmer, Paschen).
R02.12 Photoelectric Effect
- Light acting as a particle (photon).
- Threshold frequency required to eject electrons.
- Kinetic energy depends on photon frequency.