J.J. Thomson Discovers the electron e/m ratio

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Presentation transcript:

J.J. Thomson 1856 - 1940 Discovers the electron e/m ratio “Plum Pudding” model

Ernest Rutherford (1871-1937) Scattering of  (an  is 2p2n – He nucleus) surprising results:

Most Alphas are not deflected much More deflection closer to nuclei

Ernest Rutherford (1837-1937) Rutherford’s atom: (It has a nucleus) But is also has problems: Why doesn’t the electron radiate energy? How does this explain the spectral lines they had been observing? I won’t Bohr you with the solution to this right now… You can see cm, mm even .1 mm on a meter stick and that’s about it. So the smallest thing visible to you is about 1E-4 m, and atoms are about a million times smaller than that. So to picture that, know that a 1 cm stack of paper is 100 sheets, so a meter stack is 10,000 sheets, and therefore a 100 m stack would be a million sheets of paper. so one in a million is one sheet of paper compared to a stack 100 m tall. If the atom is as wide as a soccer field, the nucleus is 1 mm wide. Size of atoms – you can see E-4 m cm, mm, .1 mm, 100 papers, 1m paper 100 m paper,