It is surrounded by ‘Planetary’ electrons of radius 10 -13 cm at distances relatively greater as compared to the diameter of the electrons. It practically carries the whole mass of the atom. According to this an atom of a matter consists of a central positively charged nucleus of radius 10 -12 cm. This model was proposed by Rutherford in 1911. It was, therefore, abandoned and replaced by Rutherford’s Nuclear Atomic Model. Although Thomson model represented a considerable progress towards the truth yet the experimental evidence failed to substantiate it.įurther, it was completely given up, when it could not provide any satisfactory mechanism for explaining the large deflection suffered by Rutherford’s α-particles, scattering experiments.
ATOMIC MODEL SERIES
This is contrary to the observed facts which indicate that in the hydrogen spectrum, there are several series with each series consisting of several discrete spectral lines. Take the case of hydrogen with a single electron in its structure.Īccording to Thomson’s view regarding emission of light, hydrogen can provide only a single spectral line. Hence it ran into difficulties and rejected.
Also it could not explain the spectral series. This model could not explain the correlation of emission of frequencies of electrons in Thomson atom with the observed frequencies of light emitted by different substances. This atomic model was given up after sometime since it could not account for some observed phenomena. While the net force exerted by the positively charged sphere on each electron is toward the centre of the sphere, the electrons mutually repel each other and form shells. Thomson visualised all of the positive charge of an atom as being spread out uniformly throughout a sphere about 10 -10 m in diameter, with the electrons as smaller particles distributed in shells. Various atomic models proposed by scientists over the 1st few decades are: 1.
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