CIE IGCSE Physics

Revision Notes

5.1.1 Atomic Model

The Structure of the Atom

  • Atoms consist of small dense positively charged nuclei, surrounded by negatively charged electrons

 

Atomic model, IGCSE & GCSE Physics revision notes

An atom: a small positive nucleus, surrounded by negative electrons

(Note: the atom is around 100,000 times larger than the nucleus!)

Extended Only

Alpha Particle Scattering

  • Evidence for the structure of the atom comes from the study of α-particle scattering

 

rutherford-scattering, IGCSE & GCSE Physics revision notes

When α-particles are fired at thin gold foil, most of them go straight through but a very small number bounce straight back 

  • When α-particles are fired at thin pieces of gold foil:
    • The majority of them go straight through (A)
      This happens because the atom is mainly empty space
    • Some are deflected through small angles (B)
      This happens because the positive α-particles are repelled by the positive nucleus
    • A very small number are deflected straight back (C)
      This is because the nucleus is extremely small

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