Werner Heisenberg Atomic Model
From 1924 to 1927, Heisenberg was a Privatdozent at Göttingen, meaning he was qualified to teach and examine independently, without having a chair. From 17 September 1924 to 1 May 1925, under an International Education Board Rockefeller Foundation fellowship, Heisenberg went to do research with Niels Bohr, director of the Institute of Theoretical Physics at the University of Copenhagen. His seminal paper, "Über quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen" ("Quantum theoretical re-interpretation of kinematic and mechanical relations"), was published in September 1925. He returned to Göttingen and, with Max Born and Pascual Jordan over a period of about six months, developed the matrix mechanics formulation of quantum mechanics. On 1 May 1926, Heisenberg began his appointment as a university lecturer and assistant to Bohr in Copenhagen. It was in Copenhagen, in 1927, that Heisenberg developed his uncertainty principle, while working on the mathematical foundations of quantum mechanics. On 23 February, Heisenberg wrote a letter to fellow physicist Wolfgang Pauli, in which he first described his new principle. In his paper on the principle, Heisenberg used the word "Ungenauigkeit" (imprecision), not uncertainty, to describe it.
But the neutron was effectively discovered in 1932 by James Chadwick and the modified Ruther ford Atomic model with proton and neutron in the nucleus is as shown below:
The electron cloud model is different from the older Bohr atomic model by Niels Bohr . Bohr talked about electrons orbiting the nucleus. Explaining the behavior of these electron "orbits" was a key issue in the development of quantum mechanics . 
photon pho·ton (fō'tŏn') n. The quantum of electromagnetic energy, generally regarded as a discrete particle having zero mass, no electric charge, and an indefinitely long lifetime.
Traditional (classical) physics had assumed that particles were particles and waves were waves and thats that. However, de Broglie suggested that particles could sometimes behave as waves and waves could sometimes bahave as particles - the wave/particle duality of nature. He suggested a simple equation that would relate the two: Particles have momentum (p), waves have wavelengths ( l ) and the two are related by the equation
atom n. A unit of matter, the smallest unit of an element, consisting of a dense, central, positively charged nucleus surrounded by a system of electrons, equal in number to the number of nuclear protons, the entire structure having an approximate diameter of 10-8 centimeter and characteristically remaining undivided in chemical reactions except for limited removal, transfer, or exchange of certain electrons.
(1901-76). For his work on quantum mechanics, the German physicist Werner Heisenberg received the Nobel prize for physics in 1932. He will probably be best remembered, however, for developing the uncertainty (or indeterminacy) principle, the concept that the behavior of subatomic particles can be predicted only on the basis of probability (see uncertainty principle). Isaac Newton’s laws of motion, therefore, cannot be used to predict accurately the behavior of single subatomic particles.