Energy Level
A quantum mechanical system or particle that is bound -- that is, confined spatially—can only take on certain discrete values of energy. This contrasts with classical particles, which can have any energy. These discrete values are called energy levels. The term is commonly used for the energy levels of electrons in atoms or molecules, which are bound by the electric field of the nucleus, but can also refer to energy levels of nuclei or vibrational or rotational energy levels in molecules. The energy spectrum of a system with such discrete energy levels is said to be quantized.
If the potential energy is set to zero at infinite distance from the atomic nucleus or molecule, the usual convention, then bound electron states have negative potential energy.
If more than one quantum mechanical state is at the same energy, the energy levels are "degenerate". They are then called degenerate energy levels.
Read more about Energy Level: Explanation, History, Molecules, Energy Level Transitions, Crystalline Materials
Famous quotes containing the words energy and/or level:
“A government deriving its energy from the will of the society, and operating, by the reason of its measures, on the understanding and interest of the society ... is the government for which philosophy has been searching and humanity been fighting from the most remote ages ... which it is the glory of America to have invented, and her unrivalled happiness to possess.”
—James Madison (1751–1836)
“When science, art, literature, and philosophy are simply the manifestation of personality, they are on a level where glorious and dazzling achievements are possible, which can make a man’s name live for thousands of years. But above this level, far above, separated by an abyss, is the level where the highest things are achieved. These things are essentially anonymous.”
—Simone Weil (1909–1943)