Question

describe thomson's model of atom. which sub-atomic particle was not present in thomson's model.

Answer 1

J.J Thomson discovered the electrons by proposing the plum pudding model. Protons were absent in the model.According to him, the atoms were composed of electrons.
This model,was like a pudding in which electrons acted as plum and nucleus was the pudding.
It has a neutral charge because protons and electrons balance the charge.

Answer 2

its also called as plum pudding model.
an atom consists of a positively charged sphere and electrons are embedded in that sphere.
the positive and negative charges are equal magnitude hence, the atom as a whole electrically neutral.