Question

Which observation of rutherford's alpha scattering experiment led to the fact that there is large empty space inside the atom?

Answer 1

Observations of Rutherford’s Alpha Scattering Experiment

The observations made by Rutherford led him to conclude that:

• A major fraction of the α-particles bombarded towards the gold sheet passed through the sheet without any deflection, and hence most of the space in an atom is empty.
• Some of the α-particles were deflected by the gold sheet by very small angles, and hence the positive charge in an atom is not uniformly distributed. The positive charge in an atom is concentrated in a very small volume.
• Very few of the α-particles were deflected back, that is only a few α-particles had nearly 180^o angle of deflection. So the volume occupied by the positively charged particles in an atom is very small as compared to the total volume of an atom.

Rutherford Atomic Model

Based on the above observations and conclusions, Rutherford proposed the atomic structure of elements. According to the Rutherford atomic model:

• The positive charge and most of the mass of an atom are concentrated in an extremely small volume. He called this region of the atom as a nucleus.
• Rutherford’s model proposed that the negatively charged electrons surround the nucleus of an atom. He also claimed that the electrons surrounding the nucleus revolve around it at a very high speed in circular paths. He named these circular paths orbits.
• Electrons being negatively charged and nuclei being a densely concentrated mass of positively charged particles are held together by a strong electrostatic force of attraction.

Limitations of Rutherford Atomic Model

Although the Rutherford atomic model was based on experimental observations, it failed to explain certain things.

• Rutherford proposed that the electrons revolve around the nucleus in fixed paths called orbits. According to Maxwell, accelerated charged particles emit electromagnetic radiation and hence an electron revolving around the nucleus should emit electromagnetic radiation. This radiation would carry energy from the motion of the electron which would come at the cost of shrinking orbits. Ultimately the electrons would collapse in the nucleus. Calculations have shown that as per the Rutherford model, an electron would collapse into the nucleus in less than 10^-8 seconds. So the Rutherford model was not in accordance with Maxwell’s theory and could not explain the stability of an atom.
• One of the drawbacks of the Rutherford model was also that he did not say anything about the arrangement of electrons in an atom which made his theory incomplete.
• Although the early atomic models were inaccurate and failed to explain certain experimental results, they formed the base for future developments in the world of quantum mechanics.