CBSE Class 9 Answered

Postulate 1: An atom consists of a positively charged sphere with electrons embedded in it

Postulate 2: An atom as a whole is electrically neutral because the negative and positive charges are equal in magnitude

Above model failed to explain the stability of an atom because his model of atom failed to explain

how a positive charge holds the negatively charged electrons in an atom. Experiment performed by alpha

particle scattering indicates there is a distribution of scattered alpha particles at different angles

ranging from 0^o to 180^o as shown by following figure

Angular distribution of scattered alpha particles indicates that positive charge of atom is not distributed

throughout the size of atom but concentrated in very small region.

Also Thomson model has no explanation for the characterstic spectral lines of atoms .