Heisenberg pointed out that it is impossible to know both the exact position and the exact momentum of an object at the same time. Applying this concept to the electron we realize that in order to get a fix on an electron's position at any time, we would alter its momentum. Any attempt to study the velocity of an electron will alter its position. This concept, called the Heisenberg Uncertainty principle, effectively destroys the idea of electrons traveling around in neat orbits. Any electron that is subjected to photons will have its momentum and position affected.
Scientists now describe the possible positions of electrons in terms of probability.
Computers can calculate the points in space that an electron has the highest probability of occupying. These points can be connected to form a three-dimensional shape. Electrons are characterized in terms of the three-dimensional shapes that their probability fields define. The sum total of the various paths of electrons, traveling at very high speeds, is described as the electron cloud. G Quantum Theory Copyright 2001 Fordham Preparatory School, All Rights Reserved.