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.
Other articles related to "energy level, energy, energy levels, levels, level":
... Crystalline solids are found to have energy bands, instead of or in addition to energy levels ... Electrons can take on any energy within an unfilled band ... At first this appears to be an exception to the requirement for energy levels ...
... describing the transitions or quantum jumps between one energy level and another in a hydrogen atom ... When the electron moves from one energy level to another, a photon is given off ... Using the derived formula for the different 'energy' levels of hydrogen one may determine the energy or frequencies of light that a hydrogen atom can emit ...
... Suppose we have a number of energy levels, labeled by index i, each level having energy εi and containing a total of ni particles ... Suppose each level contains gi distinct sublevels, all of which have the same energy, and which are distinguishable ... distinguishable from each other, yet they can still have the same energy ...
... occurs in systems with a limited number of energy levels so that E(T) increases with sharp steps, one for each energy level that becomes available ... At zero temperature only the lowest energy level is occupied, entropy is zero, and there is very little probability of a transition to a higher energy level ... approaches the difference between the energy levels there is a broad peak in the specific heat corresponding to a large change in entropy for a small change in temperature ...
... different quantum states are said to be degenerate if they are all at the same energy level ... Conversely, an energy level is said to be degenerate if it contains two or more different states ... The number of different states at a particular energy level is called the level's degeneracy, and this phenomenon is generally known as a quantum degeneracy ...
Famous quotes containing the words level and/or energy:
“For him nor deep nor hill there is,
But alls one level plain he hunts for flowers.”
—Unknown. The Thousand and One Nights.
AWP. Anthology of World Poetry, An. Mark Van Doren, ed. (Rev. and enl. Ed., 1936)
“Reckoned physiologically, everything ugly weakens and afflicts man. It recalls decay, danger, impotence; he actually suffers a loss of energy in its presence. The effect of the ugly can be measured with a dynamometer. Whenever man feels in any way depressed, he senses the proximity of something ugly. His feeling of power, his will to power, his courage, his pridethey decline with the ugly, they increase with the beautiful.”
—Friedrich Nietzsche (18441900)