#Bohr's atomic theory full#

If this balance were not present, the electron would either fall into the nucleus, or it would be flung out of the atom. The planetary model of the atom assumed that the electrostatic attraction between the central nucleus and the electron is exactly balanced by the centrifugal force created by the revolution of the electron in its orbit. This led him to suggest the planetary model of the atom, in which the electrons revolve in orbits around the nuclear 'sun'.Įven though the planetary model has long since been discredited, it seems to have found a permanent place in popular depictions of the atom, and certain aspects of it remain useful in describing and classifying atomic structure and behavior.

Ernest Rutherford, a New Zealander who started out as Thompson's student at Cambridge, distrusted this 'plum pudding' model (as he called it) and soon put it to rest Rutherford's famous alpha-ray bombardment experiment (carried out, in 1909, by his students Hans Geiger and Ernest Marsden) showed that nearly all the mass of the atom is concentrated in an extremely small (and thus extremely dense) body called the nucleus. The demonstration by Thompson in 1867 that all atoms contain units of negative electric charge led to the first science-based model of the atom which envisaged the electrons being spread out uniformly throughout the spherical volume of the atom. We will therefore present the theory in a semi-qualitative manner, emphasizing its results and their applications, rather than its derivation. In order to develop and present this theory in a comprehensive way, we would require a number of mathematical tools that lie beyond the scope of this course.

#Bohr's atomic theory full#

The modern theory of the atom makes full use of the wave-particle duality of matter. Our goal in this unit is to help you understand how the arrangement of the periodic table of the elements must follow as a necessary consequence of the fundamental laws of the quantum behavior of matter. Explain the relation between the absorption and emission spectrum of an atom.Describe the way in which Bohr's quantum numbers explain the observed spectrum of a typical atom.What is an atomic line emission spectrum? What is the significance of the continuum region of an emission spectrum? Sketch out a drawing showing the essentials of such a spectrum, including the ionization limit and the continuum.Sketch out a diagram showing how the concept of a standing wave applies to the description of the electron in a hydrogen atom.Give an example of a mechanical standing wave state the meaning and importance of its boundary conditions.

State the major concepts that distinguished Bohr's model of the atom from the earlier planetary model.

Describe the Thompson, Rutherford, and early planetary models of the atom, and explain why the latter is not consistent with classical physics.

Make sure you thoroughly understand the following essential ideas: