RUTHERFORD THEORYAlbert C. X10/1 | Julius C. X10/13 | Nicholas S.W. X10/17 | Sinclair K. X10/19
Lenard’s ExperimentLenard’s experiment was meant to proof that if Thomson’satomic model is right, electrons that go through thealuminum plate should’ve experienced energy loss, so theelectrons should be easily refracted.In Lenard’s experiment, he shows that Thomson’s atomicmodel is wrong because he found that most of the electronswere not refracted. This shows that electrons are not spreadevenly.
Continuation of Lenard’s ExperimentIn 1911, Ernest Rutherford was interested to continueLenard’s experiment by replacing electrons withparticle which consist of positive charge. Thisexperiment was conducted by Hans Geiger & ErnstMarsden.
Who is Ernest Rutherford?He is a New Zealand-born, British chemist andphysicist. In 1914, he was knighted and twoyears later, he was awarded the HectorMemorial Medal. Under him, Nobel Prizes wereawarded to James Chadwick for discoveringneutron. Rutherford remains the only scienceNobel Prize winner to have performed his mostfamous work after receiving the prize.
Rutherford’s research• “rays” / particles• Theory of protons• Detector for electromagnetic waves
What are rays / particles?• High speed particles• Made up of two protons and two neutrons• Is a nucleus, same as the nucleus of a common atom of helium• Don’t have electrons around it• Type of ionizing radiation• will loose all their energy in just a couple inches of travel in air
What Rutherford did?He directed the rays to a gold platesurrounded by screen coated with sulfide zincwhich are around the plate.
What happened?1. Some of the particles pass the empty space go trough Nucleus Particles Atoms of Gold foil
2. Some of the particles that approach the nucleus are deflected Nucleus Particles Atoms of Gold foil
3. Some of the particles that hits the nucleus are bounced back Particles Nucleus Atoms of Gold foil
Conclusion of Rutherford’s Theory• A large fraction of the room in an atom is empty – Indicated by most of rays pass through the plate Nucleus Particles Atoms of Gold foil
• Nucleus is tiny yet very dense core of atom – Indicated by little amount of refracted rays Particles Nucleus Atoms of Gold foil
• Electrons go circle the nucleus with high speed – Indicated by the electrons that are not attracted by protons inside the nucleus
• The charge of the nucleus is the same as particle’s, which is positive – Indicated by the deflected rays that deflected due to repulsion forces of similar charge. Nucleus Particles Atoms of Gold foil
Rutherford’s Theory WeaknessBased on Rutherford’s theory thatstates electrons go around thenucleus will stay on its path isunproved. Based on physicsclassical mechanic law, that objectsthat going around on circular pathwill release its energy in the form ofradiation, so the electron will begoing closer to the nucleus. Butthen, Rutherford’s theory issupported by Bohr’s theorem.