Question

Large angle scattering of \(\alpha-\) particle could not be explained by (A) Thomson model (B) Rutherford model (C) Both Thomson and Rutherford model (D) neither Thomson nor Rutherford model

Short answer

The large angle scattering of alpha particles could not be explained by the Thomson model (A), in which electrons are dispersed evenly throughout the atom's volume. This model doesn't predict significant deflections due to the lack of centrally concentrated positive charge. On the other hand, Rutherford's model, with a dense, positively charged nucleus, does predict large deflections and is supported by experimental evidence.

Step-by-step solution

Understand Thomson's Model

In the Thomson model of the atom, the electrons are dispersed evenly throughout the atom's volume, nicknamed as the "plum pudding model". According to this model, positively charged alpha particles would pass through the uniformly charged negatively charged "cloud" of electrons with only little deflections due to the slight repulsions or attractions by the electrons' negative charges.

Understand Rutherford's Model

In the Rutherford model, also known as the Planetary model, the atom consists of a dense, positively charged nucleus surrounded by electrons in orbits. According to this model, the alpha particles could pass close to the nucleus, altering their path dramatically due to the intense electrostatic repulsion between the positively charged alpha particles and the positively charged nucleus.

Determine which model cannot explain large angle scattering

In Thomson's model, significant large-angle scattering of alpha particles would not be expected because there is no centrally concentrated positive charge to cause large deflection. In contrast, Rutherford's model does predict large angle deflections if alpha particles pass near the atom's nucleus. Experiments, such as Rutherford's gold foil experiment, have proven large angle scattering to be real, thereby validating Rutherford's model and invalidating Thomson's model concerning large angle scattering.

Select the correct answer

Based on the analysis above, Thomson's model could not explain large angle scattering of alpha particles. Therefore, the correct answer is: (A) Thomson model