| "... the existence of uncertainty need not be a | | | | description of the probability of finding electrons in |
| source of humiliation for science ... If a tiny, but | | | | certain areas of space. These solutions in the |
| crucial, uncertainty is part of the fabric of the | | | | form of numbers are called quantum numbers. |
| universe, it is a tribute to scientists to have | | | | Quantum numbers not only describe specific |
| discovered the fact." --Isaac Asimov | | | | quantized energy states for the electron but also |
| The Uncertainty Principle | | | | a set of probabilities for the position of the |
| In 1927, Werner Heisenberg proposed from a | | | | electron in a given energy level. These probable |
| purely theoretical view that it was impossible to | | | | positions known as atomic orbitals refer to a |
| know both the position and momentum of the | | | | region in space where an electron might be found, |
| electron simultaneously. This idea, which became | | | | whereas an orbit is a definite path in space. Since |
| known as the uncertainty principle, dealt with the | | | | the orbital does not have definite boundaries, it is |
| probability of an electron's position in a region of | | | | sometimes referred to as an electron cloud. |
| space rather than its exact position. | | | | Three of the quantum numbers came directly |
| The uncertainty principle was hard for many | | | | from the Schrödinger equation. A fourth |
| scientists to accept. If they accepted this idea of | | | | quantum number was added later by Paul Dirac to |
| uncertainty, it meant that man was not capable | | | | account for the affects of relativity. Together, |
| of all knowledge and science might not be able to | | | | these four quantum numbers can be used to |
| explain everything. But, not even Einstein could | | | | describe the probable location of each electron. |
| find a suitable reason not to accept the new idea. | | | | More importantly, quantum numbers can describe |
| In view of the uncertainty principle, Max Born, in | | | | the electron configurations (electron |
| 1928, suggested that the solutions to the | | | | arrangements) in all atoms. |
| Schrödinger wave equation be taken as a | | | | |