HISTORY OF ATOM

Before the discovery of electron what were atoms thought to be

tiny spheres that cannot be divided

What did the discovery of the electron lead to

the plum pudding model

What did the plum pudding model suggest

that the atom is a ball of positive charge with negative electrons embedded in it

What did the results of the alpha particle scattering experiment lead to

The mass of an atom is concentrated at the centre and is charged.

Who adapted the nuclear model

Niels Bohr

What did Niels Bohr do

suggested that electrons orbit the nucleus at specific distances

What did later experiments lead to

the idea that the positive charge of any nucleus could be divided into a number of smaller particles

What did James Chadwick provide evidence for

The existence of neutrons within the nucleus

How did the scattering experiment lead to a change in the atomic model

Some particles were deflected; the mass of an atom is concentrated in the middle. Some particles passed through; an atom is mostly empty space. Some particles were reflected; The mass is the middle is positively charged.

What is the difference between the plum pudding model and the nuclear model

The nuclear model has mostly empty space, the mass is concentrated in the nucleus, the electrons and nucleus are seperate