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J.J Thomson
- Credited with Electron Discovery
Showed Cathode Rays were composed of unknown negatively charged
particlesMax Planck 1900
- Originator of Quantum theory
o His findings were counter to all existing physical study.
- Suggested radiation is quantized – Travels in discrete amountsAlbert Einstein 1905
- Takes Planck’s ideas seriously, proposes quantum of light – the photon which behaves like a particle.
- Explained equivalence of mass and energy
- Suggested particle-wave duality of photons
o The Equivalence principle
- Special relativity
- Explains the curvature of space-time 1912Ernest Rutherford 1911
- Leads team of Hans Geiger and Ernest Marsden to conduct famous alpha particle, gold foil experimentErnest Rutherford
- He infers the existence of the nucleus as result of the experiment. 1919Niels Bohr 1913
- Constructs a theory of atomic structure based on quantum ideas
- Developed the complementarity principle.
o Bohr’s Postulates
- Electrons in an atom exist in Stationary states
- Transmission between stationary states produces/absorbs
EM radiation
- The Angular momentum of stationary electron is quantisedJames Chadwick 1921
- With the assistance of E.S Bieler conclude the existence of a strong force binding the nucleus togetherJames Chadwick 1931
- Discovers the existence of the Neutron.Louis de Broglie 1924
- Postulated the wave nature of electrons and suggested that all matter has wave properties.
o The “de Broglie hypothesis” led to the birth of wave mechanics.
o “If particles can act as wave, waves can act as particles”
- Davisson and Gerner experiment
o Confirmed the wave nature of electronsWolfgang Pauli 1925 – January
- Applies quantum understanding to the hydrogen atom.
- Formulates exclusion principle for electrons in an atom.
o No two electrons could exist in the same quantum
- Identified by four quantum numbers including his new two-valued degree of freedom.
Later called Electron SpinEnrico Fermi:
- Alongside C.N Yang suggest that a pion is a composite structure of a nucleon and an anti-nucleon. (Highly radical idea) 1949Периоды
Enrico Fermi 1933-34
- Puts forward the theory of beta decay that introduces the weak interaction. First theory to explicitly use neutrinos and particle flavour changes.
- Created first nuclear reactor
- Experimented with inducing radioactivity with recently discovered neutrons, discovered slow neutrons were easily captured.
o Fermi Age Equation
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