atomic model - scientific discoveries

Who was James Chadwick?

The scientist that proved the existence of neutrons, as the nuclear model didn't explain the atomic mass atoms had.

How was Chadwick's discovery relevant to isotopes?

It showed that all isotopes have the same number of protons but different numbers of neutrons.

What were some of the features of the plum pudding model?

It was a ball of positive charge, with electrons spread throughout it, embedded into the ball of positive charge. The mass was spread throughout and there is no empty space in the atom.

Who proposed the idea of the plum pudding model?

JJ Thomson

Who proposed the nuclear model of the atom?

Ernest Rutherford

What were some differences between the nuclear and plum pudding model?

In the nuclear model, the positive charge was concentrated in the middle as a nucleus, the electrons were outside the nucleus, it was mostly empty space and the mass is concentrated at the centre. In the plum pudding model, positive charge was spread throughout, electrons were embedded into the nucleus, there was no empty space and mass was spread throughout.

How did Rutherford learn that the plum pudding model was wrong?

During the alpha scattering experiment, it was expected for the alpha particles to pass straight through, but some of the particles were deflected/bounced back. This meant there had to be a positive nucleus in the centre of the atom.

What were the conclusions of the alpha scattering experiment?

Most particles passed through, therefore an atom is mostly empty.

Some particles were deflected, therefore there is a positive nucleus in the centre of an atom.

How did Neils Bohr adapt the nuclear model?

He suggested that electrons orbit the nucleus at specific distances