What is Energy level: Definition and 140 Discussions

A quantum mechanical system or particle that is bound—that is, confined spatially—can only take on certain discrete values of energy, called energy levels. This contrasts with classical particles, which can have any amount of energy. The term is commonly used for the energy levels of the electrons in atoms, ions, 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.
In chemistry and atomic physics, an electron shell, or principal energy level, may be thought of as the orbit of one or more electrons around an atom's nucleus. The closest shell to the nucleus is called the "1 shell" (also called "K shell"), followed by the "2 shell" (or "L shell"), then the "3 shell" (or "M shell"), and so on farther and farther from the nucleus. The shells correspond with the principal quantum numbers (n = 1, 2, 3, 4 ...) or are labeled alphabetically with letters used in the X-ray notation (K, L, M, N…).
Each shell can contain only a fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the nth shell can in principle hold up to 2(n2) electrons. Since electrons are electrically attracted to the nucleus, an atom's electrons will generally occupy outer shells only if the more inner shells have already been completely filled by other electrons. However, this is not a strict requirement: atoms may have two or even three incomplete outer shells. (See Madelung rule for more details.) For an explanation of why electrons exist in these shells see electron configuration.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 an atom, ion, or molecule is at the lowest possible energy level, it and its electrons are said to be in the ground state. If it is at a higher energy level, it is said to be excited, or any electrons that have higher energy than the ground state are excited. If more than one quantum mechanical state is at the same energy, the energy levels are "degenerate". They are then called degenerate energy levels.

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  1. hongseok

    B Is it possible to find the energy level of a hydrogen atom in this way?

  2. RobbyQ

    I Stimulated Emission & Emitted photon direction

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  3. H

    Degeneracy of the energy level

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  4. N

    B Energy needed for electron's change in energy level in an atom

    Textbooks always give an explanation for why electrons move between energy levels in atoms with an explanation something like this: 'An electron can jump to a higher energy level if it absorb's energy which exactly matches the difference between final and initial energy level'. My question...
  5. Adams2020

    What is the recoil energy of a nucleus produced in its first energy level?

    Table: To solve, using the conservation of energy: E0=(m(deutron)+m(16O)-m(17O)-m(p))c^2 so: E0=(2.014+15.994-16.999-1.008)931.5=0.93 MeV. so using the conservation of energy: 14.95+0.93=16.62+0+E' E'=- 0.74 MeV But the energy sign has become negative. I also calculated for the first excited...
  6. E

    Definition of energy level width

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  7. WMDhamnekar

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  8. Adrian Tudini

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  9. A

    Partition function of 2 bosons in two energy level 0 and E

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  10. LordWhiplash

    I Why is the lowest energy level close to the center?

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  11. F

    I Why does the energy level of an electron in an atom have a width?

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  12. M

    A Qubit Energy Level Required to be Unevenly Separated

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  13. Haynes Kwon

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  14. S

    Can Electrons Carry Infinite Energy?

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  15. F

    Can a photon with energy greater than energy level difference of atom.

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  16. J

    I Mass for solving the nuclear energy level

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  17. C

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  18. M

    Why Use Nuclear Charge In Finding Energy Value of Singular Electron?

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  19. Edge5

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  20. E

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  21. Physics345

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  22. G

    B Spontaneous increase in energy level

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  23. L

    Determining which energy level transfers cause peaks in x-ray spectra

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  24. MARX

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  25. D

    I How Does Rubidium's Electron Spin Affect Its Energy Levels?

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  26. barryj

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  27. J

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  28. Wrichik Basu

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  29. A

    I Change in electron energy level and photon emission....

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  30. Arman777

    I Why CERN Energy Level Seems Low?

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  31. allanwinters

    Grade 12 chemistry homework help -- 2n^2 electrons possible in each energy level

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  32. S

    I Energy Level Change in Adiabatic Reversible Process

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  33. B

    Two energy level system calculate average occupancy

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  34. NaiveTay

    I Can a Photon be Absorbed Without the Exact Energy Level?

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  35. DetectiveT

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  36. C

    Equation for the energy of an electron

    Hello, I would like to thank all of the contributors on this site. You have helped me in more ways than I can count. I am struggling with the following concept and was wondering if anyone could clarify this. As the electron gets further away from the nucleus, its energy increases. This makes...
  37. ptownbro

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  38. ptownbro

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  39. T

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  40. Tonia

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  41. mss90

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  42. 1

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  43. CAH

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  44. A

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  45. Z

    How to find the energy level if a three state system

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  46. K

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  47. T

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  48. O

    Calculating Initial Energy Level for Emitted Photons

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  49. L

    Confusion Over Same Energy Level Transitions

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  50. A

    Individual states of a particular energy level

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