science 7

1. Atomic Models Through History
• From Ancient Philosophy to Quantum
Mechanics
• Presented by: [Your Name]
• Date: [Insert Date]

2. Introduction
• • What is an atomic model?
• • Why do atomic models change over time?
• • Importance of understanding the atom

3. Democritus' Model (400 B.C.)
• • First concept of the atom: indivisible
particles
• • “Atomos” = uncuttable
• • No scientific evidence, just philosophical
idea

4. Dalton’s Atomic Theory (1803)
• • All matter is made of atoms
• • Atoms of the same element are identical
• • Atoms cannot be created or destroyed
• • Atoms combine in fixed ratios
• Model: Solid sphere model (like a billiard ball)

5. Thomson’s Model (1897)
• • Discovered the electron
• • Plum Pudding Model: positive sphere with
embedded electrons
• • Cathode ray tube experiment

6. Rutherford’s Model (1911)
• • Gold foil experiment
• • Atom is mostly empty space
• • Dense positive nucleus with electrons
orbiting around

7. Bohr’s Model (1913)
• • Electrons orbit the nucleus in energy levels
• • Each orbit has fixed energy
• • Explains spectral lines of hydrogen

8. Quantum Mechanical Model
(Modern)
• • Electron cloud model
• • Based on probability, not fixed paths
• • Developed by Schrödinger, Heisenberg, and
others

9. Comparison of Models
• Dalton - Solid sphere (John Dalton)
• Thomson - Electrons in positive soup (J.J.
Thomson)
• Rutherford - Nucleus, electrons orbit (E.
Rutherford)
• Bohr - Energy levels (Niels Bohr)
• Quantum - Electron clouds, orbitals
(Schrödinger, etc.)

10. Real-World Applications
• • Nuclear energy
• • Medical imaging
• • Chemistry & material science

11. Quiz or Recap
• Example question:
• “Which model introduced energy levels?” –
Bohr

12. References
• • Textbooks, articles, images, or websites used