Rutherford's Atomic Model

Introduction

• Proverb Reference: "Indigo blue is extracted from the indigo plant but is bluer than the plant it comes from" - Chinese proverb illustrating a student surpassing the teacher.
• Historical Example: Ernest Rutherford surpassing J. J. Thomson in understanding atomic structure.

Background on Atomic Structure

• Components of Atoms:
  • Protons
  • Neutrons
  • Electrons
• Discovery through hypotheses and experiments.

J. J. Thomson's Plum Pudding Model (1897)

• Electron Discovery: Led to the hypothesis of atom neutrality.
• Model Description:
  • Electrons embedded in a positively charged "cloud".
  • Similar to "raisins in plum pudding".
• Limitations:
  • Stability of coexisting charges questioned.
  • Unaccounted atomic mass.

Ernest Rutherford's Gold Foil Experiment (1909)

• Team: Hans Geiger and Ernest Marsden.
• Experiment Setup:
  • Radium emits alpha particles through a small hole.
  • Alpha particles directed at thin gold foil.
  • Surrounding zinc-sulfide screen detects scattered particles.
• Expected Results:
  • Most particles pass through.
  • Slight deflections by electrons.
• Unexpected Observations:
  • Large-angle deflections.
  • Some particles bounced backward.

Discovery of the Atomic Nucleus

• Conclusion:
  • Presence of a positive, heavy, central nucleus.
  • Protons identified as positively charged particles.
  • Atom mostly empty space.

Rutherford's Nuclear Model

• Model Proposal:
  • Tiny nucleus with protons inside.
  • Electrons surround the nucleus.
  • Atom neutrality from equal number of protons and electrons.
• Contradictions:
  • Classical electrodynamics: charged particles should radiate energy and collapse the atom.
  • Energy radiation should form continuous spectrum, but observed line spectrum.

Impact and Recognition

• Contributions:
  • Fundamental understanding of atomic structure.
  • Nobel Prize awarded for his research.

Conclusion

• Continuation of atomic model development.
• Next steps: Further refinement of Rutherford’s ideas in subsequent models.
• Appreciation to supporters and patrons.