How does Bohr's model of the atom differ from Rutherford's?

2 Answers
Jul 22, 2014

Thanks for your question about atomic models.

Rutherford knew the electrons were outside of the nucleus and they were equal in number to the "positiveness" of the nucleus. Rutherford randomly placed the negative electrons outside the nucleus.

Bohr's improvement of the Rutherford model was that Bohr placed the electrons in distinct energy levels. This Bohr model matched the experimental data that Max Planck had determined from his work on the different energies of photons.

If you will search Rutherford and Bohr models of the atom and narrow your search to images, you will find some of the models.

Hope this helps.

Aug 12, 2014

Rutherford described the atom as consisting of a tiny positive mass surrounded by a cloud of negative electrons. Bohr thought that electrons orbited the nucleus in quantised orbits.

Bohr built upon Rutherford's model of the atom. In Rutherford's model most of the atom's mass is concentrated into the centre (what we now call the nucleus) and electrons surround the positive mass in something like a cloud.

Bohr's most significant contribution was the quantisation of the model. He believed that electrons moved around the nucleus in circular orbits with quantised potential and kinetic energies. So it was not possible for electrons to occupy just any energy level.

In principle the quantisation aspect of the model is still believed to be correct. The main problem lies in the idea of electrons in circular orbits. This does not satisfy the Heisenberg uncertainty principle, which is that it is not possible to know the position and momentum of a particle simultaneously.

For further reading you might want to find out more about what scientists currently believe about atomic structure: