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Lord Rutherford’s Atomic model

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Topics

  • Introduction
  • Rutherford’s Nuclear atomic model
  • Merits and Demerits

Introduction:

In 1911, Ernest Rutherford, a renowned physicist, introduced a groundbreaking model of the atom known as the Nuclear Model. This model emerged from his famous gold foil experiment, which revealed that the atom has a dense, positively charged centre called the nucleus. Rutherford’s work challenged the previously accepted plum pudding model by J.J. Thomson and fundamentally changed our understanding of atomic structure. The nuclear model proposed that electrons orbit around the nucleus in mostly empty space, explaining the atom’s structure in a completely new way.

Rutherford presented his theory of the structure of atoms. For this theory, he was awarded the Nobel Prize for chemistry.

 
Rutherford

Rutherford’s Nuclear atomic model

Rutherford’s Gold Foil Experiment:

Rutherford used a very thin sheet of gold foil, only 0.0001 mm thick, and bombarded it with positively charged α-particles (alpha particles) emitted by a radioactive substance. He placed a fluorescent screen around the gold foil to observe how the α-particles behaved when they struck the foil.

Rutherford’s scattering experiment

Observations,

  1. Most α-particles passed straight through: Rutherford observed that a majority of the α-particles went straight through the gold foil without any change in direction. This indicated that atoms have a lot of empty space inside.
  2. Some α-particles were detected slightly: A few α-particles were deflected at small angles. This suggested that they encountered a positively charged obstacle within the atom.
  3. A few α-particles deflected sharply or bounced back:A very small number of α-particles were deflected at large angles or even bounced back in the opposite direction. This surprising result indicated that the α-particles had collided with a dense, positively charged mass in the centre of the atom.

Following were his conclusions from the α-particle scattering experiment:

  1. Most of the space inside the atom is empty because most of the α-particles passed through the gold foil without getting deflected.
  2. Very few particles were deflected from their path, indicating that the positive charge of the atom occupies very little space.
  3. A very small fraction of α-particles were deflected by 1800, indicating that all the positive charge and mass of the gold atom were concentrated in a very small volume within the atom.

Merits and Demerits:

Merits  Demerits
There is a positively charged centre in an atom called the nucleus. Nearly all the mass of an atom resides in the nucleus. This model was unable to explain the stability of an atom.
The electrons revolve around the nucleus in circular paths. The size of the nucleus is very small as compared to the size of the atom. The theory was incomplete as it did not mention anything about the arrangement of electrons in the orbit.
Demonstrated that atoms are mostly empty space, explaining alpha particle behaviour. Failed to explain the line spectra of an atom.
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Rutherfords alpha-particle scattering experiment
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Related QuestionsVIEW ALL [37]

To study the internal structure of the atom, Rutherford used ______.

In Rutherford’s experiment, the bouncing of alpha particles suggests that the nucleus of an atom is negatively charged.

What conclusions were made from the observations of Gold foil experiment?

State true or false. If false, correct the statement.

In an atom, electrons revolve around the nucleus in fixed orbits.

What do you think would be the observation if the α-particle scattering experiment is carried out using a foil of a metal other than gold?

Rutherford's alpha particle scattering experiment led to the discovery of :

State whether the following statement is true or false :
Thomson proposed that the nucleus of an atom contains protons and neutrons.

Rutherford’s alpha-particle scattering experiment was responsible for the discovery of ______.

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