Kami BS and MSC Physics Notes

WHAT IS THE PURPOSE OF A LITERATURE REVIEW

Waves or particles? What if everything is both?

Welcome to the mind-bending world of Wave-Particle Duality — a cornerstone of quantum mechanics that shattered classical thinking.

From photons to electrons, light to matter—everything shows dual behavior depending on how we look at it!

Abdul Wali Khan University Mardan AWKUM Media Cell Awkum Voice Department of Physics AWKUM Waves Physics and Maths Problem Solving AIST Optics Science

ATOMIC MODEL THROUGHOUT HISTORY
1. John Dalton’s Model (1803) – Solid Sphere Model

Overview:
Dalton proposed that all matter is made up of indivisible particles called atoms.

He imagined atoms as tiny, solid spheres—like billiard balls.

Key Ideas:
Atoms of the same element are identical in mass and properties.

Atoms cannot be created, divided, or destroyed.

Compounds form when atoms of different elements combine in fixed ratios.

Importance:

First scientific model of the atom based on experimental evidence (like gas laws).

Laid the groundwork for modern chemistry.

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2. J.J. Thomson’s Model (1904) – Plum Pudding Model

Overview:
After discovering the electron, Thomson proposed that atoms are made of a positively charged substance with negatively charged electrons scattered within it—like raisins in pudding.

Key Ideas:
Atoms are divisible.

Electrons are negatively charged subatomic particles.

The rest of the atom is a blob of positive charge to balance the electrons.

Importance:

First model to show that atoms have internal structure.

Introduced the idea of subatomic particles.

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3. Ernest Rutherford’s Model (1911) – Nuclear Model

Overview:
Conducted the gold foil experiment where alpha particles were fired at a thin sheet of gold.

Most passed through, but some were deflected at large angles.

Key Ideas:
Atoms are mostly empty space.

A small, dense, positively charged nucleus is at the center.

Electrons orbit around this nucleus.

Importance:

Disproved the plum pudding model.

Introduced the concept of a nucleus.

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4. Niels Bohr’s Model (1913) – Planetary Model

Overview:
Bohr expanded on Rutherford’s model using discoveries from quantum theory.

Key Ideas:
Electrons orbit the nucleus in fixed paths or “energy levels.”

Each level has a specific amount of energy.

Electrons can jump to higher levels when energy is absorbed and fall back down when energy is released (as light).

Importance:

Explained why atoms emit light in specific colors (atomic spectra).

Added the concept of quantized energy levels.

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5. Erwin Schrödinger’s Model (1926) – Quantum Mechanical Model (Electron Cloud Model)

Overview:
Schrödinger used complex math to describe the behavior of electrons as waves, not particles in orbits.

Key Ideas:
Electrons exist in regions called orbitals (not fixed paths).

Orbitals show where an electron is most likely to be found.

The exact location and momentum of an electron cannot be known at the same time (Heisenberg Uncertainty Principle).

Importance:
Most accurate and widely accepted model today.

Forms the basis of quantum chem and modern physics.

Polygons Explained Visually – From Triangle to Decagon! 🔺🔷
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*Purpose of a literature review!!*