Historical Development of Atomic Theory
⚛️ Democritus proposed the concept of indivisible particles called "atomos" around 440 BCE, suggesting they varied in size and shape.
📜 John Dalton, in 1808, challenged Aristotelian theory, concluding that compounds are combinations of atoms of different elements that cannot be created or destroyed, based on consistent elemental proportions.
⚡️ J.J. Thompson's discovery of the electron in 1897 led to the "chocolate chip cookie model," depicting atoms as spheres of positive matter embedded with negative electrons.

Evolution of the Atomic Model
🌟 Ernest Rutherford, building on Thompson's work, discovered the nucleus by observing alpha particles bouncing back from gold foil, concluding that atoms are mostly empty space with mass concentrated centrally.
🪐 Niels Bohr expanded Rutherford's model in 1913, proposing that electrons orbit the nucleus at fixed energy levels, referencing work by Planck and Einstein.
🌊 The development of quantum mechanics revealed that electrons behave as waves and are governed by the Heisenberg Uncertainty Principle, meaning their exact position and speed cannot be known simultaneously.

Key Points & Insights
➡️ The concept of the atom originated with the Greek philosopher Democritus over 2,400 years before modern scientific confirmation.
➡️ John Dalton's atomic theory was foundational, establishing that elements combine in fixed proportions to form compounds.
➡️ The shift to the quantum model recognized electrons as existing within a range of possible locations rather than fixed orbits.
➡️ Atomic theory explains phenomena like fireworks, where energy shifts between electron energy levels release light at specific wavelengths.

📸 Video summarized with SummaryTube.com on Nov 27, 2025, 00:38 UTC