Question

How was Bohr’s model modified in the modern quantum atomic model?

Answer 1

The structural model of atom starting from Thomson Plum model to Rutherford experiments and observation. The atoms structure was not confirmed in the Rutherford model; it has some drawbacks for the electrons movement around the nucleus which is against the law of electrostatic charge. This was overcome by the suggestions given by Bohr Theory.

Complete Answer:
We know that there are some issues with the Rutherford model, in that Rutherford describes that electrons move around the nucleus like planets move around the sun. So, the limitation of that model gets satisfied by the explanation given by Bohr’s model.

Bohr gives the remedy for stability problems. He said that the electrons which are moving around the nucleus in orbits possess a certain amount of energy and the energy transaction is possible only when an electron jumps from higher to lower orbitals and from lower to higher orbitals. The jumping from lower to higher orbital results when excitation happens while the jumping from higher to lower happens when they lose their energy. It was also stated that an electron is stable when it is in its smaller orbit.

There are some spectra formed when the jumping of electrons happen and we get certain lines called Lyman, Balmer, Paschen, Bracket and Pfund. The packets of energy released were called quanta and given by scientist “Plank”, the usefulness of Bohr Theory gave spectrum for hydrogen atom.

As we know that there are some drawbacks in every theory, here also in Bohr’s theory the drawback is that Bohr Theory doesn’t give an explanation about the spectrum of more than one electron system. Like if we take an example of a helium atom we know that it has two electrons in the outermost orbit so its structural spectrum was not formed taking Bohr Theory in consideration.

Note: The movement of electrons around the nucleus is in particular shells and hence, as given by Bohr. This was explained in terms of charged particles and their electrostatic attraction. When the electrons move around the nucleus which is a positive charged body, there must be some attraction between them. By this attraction the electrons could get well into the nucleus. So the Rutherford theory fails.