Question
Explain the Rutherford atomic model and its limitation.
✓
Answer
As the planets revolves around the Sun, Rutherford suggested in the proposed atomic model, that nucleus at the centre and the electrons orbiting it around the nucleus.
$\rightarrow$ Thus the basic difference between the two is that the planets in the system of Sun are captured by gravitational force while the nucleus electron intersects according Coulomb law in a atom.
$\rightarrow$ The limitation of the Rutherford atomic model: According to classical physics, there is no constraint on the radius of the orbit of electron.
$\rightarrow$ Electron moving in a circular orbit performs an acceleration motion.
$\rightarrow$ According to classical electromagnetic theory an accelerated charge radiates energy in the form of electromagnetic radiation hence its energy goes on decreasing.
$\rightarrow$ Hence, its orbit would not be circular, it will be spiral terminating at its nucleus which is shown in the figure.
$\rightarrow$ Thus, such an atom cannot be stable.
$\rightarrow$ Further, according to the classical electromagnetic theory, the frequency of the electromagnetic wave emitted by the revolving electrons is equal to the frequency of revolution.
$\rightarrow$ As the electrons spiral inwards, their angular velocities and hence their frequencies would change continuously and so will the frequency of the light emitted. Thus, they would emit a continuous spectrum in contradiction to the line spectrum actually observed.
$\rightarrow$ Hence, Rutherford's atomic model states that classical ideas are not sufficient to explain the atomic structure. Because, this model fails to understand the stability of atom.
$\rightarrow$ Thus the basic difference between the two is that the planets in the system of Sun are captured by gravitational force while the nucleus electron intersects according Coulomb law in a atom.
$\rightarrow$ The limitation of the Rutherford atomic model: According to classical physics, there is no constraint on the radius of the orbit of electron.
$\rightarrow$ Electron moving in a circular orbit performs an acceleration motion.
$\rightarrow$ According to classical electromagnetic theory an accelerated charge radiates energy in the form of electromagnetic radiation hence its energy goes on decreasing.
$\rightarrow$ Hence, its orbit would not be circular, it will be spiral terminating at its nucleus which is shown in the figure.
$\rightarrow$ Thus, such an atom cannot be stable.
$\rightarrow$ Further, according to the classical electromagnetic theory, the frequency of the electromagnetic wave emitted by the revolving electrons is equal to the frequency of revolution.
$\rightarrow$ As the electrons spiral inwards, their angular velocities and hence their frequencies would change continuously and so will the frequency of the light emitted. Thus, they would emit a continuous spectrum in contradiction to the line spectrum actually observed.
$\rightarrow$ Hence, Rutherford's atomic model states that classical ideas are not sufficient to explain the atomic structure. Because, this model fails to understand the stability of atom.
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