ICSE Class 8 Answered

In 1911, Earnest Rutherford, a scientist from New Zealand, overturned Thomson’s atomic model by his gold foil experiment. His experiment demonstrated that the atom has a tiny massive nucleus. It thus rejected Thomson’s model of the atom.

•  There is a positively charged centre in the atom called the nucleus in which nearly all the mass of the atom is concentrated.
•  Negatively charged particles called electrons revolve around the nucleus in paths called orbits.
•  The size of the nucleus is very small as compared to the size of the atom.
• His model can be compared to the solar system where the planets are compared with electrons and the sun with the nucleus.

Drawbacks of Rutherford’s Model of an Atom

• Rutherford’s atomic model could not explain how the moving electrons could remain in its orbit.
• Any charged particle during acceleration would give out energy, and while revolving it would lose energy and eventually fall into the nucleus.
• This means that the atom would be highly unstable.
• But matter is composed of stable atoms.