Answer: As new discoveries are made, existing theories are revised or replaced.
Dalton stated that atom is matter that can not be divided.
His "plum pudding" model (1904) suggested: the electrons are embedded in the positive charge.
J. J. Thomson discovered the electron in 1897.
According to Rutherford model of the atom:
1) Atoms have their charge concentrated in a very small nucleus.
2) Major space in an atom is empty.
3) Atoms nucleus is surrounded by negatively charged particles called electrons.
4) An atom is electrically neutral.
Step-by-step explanation: