What is Electron configuration: Definition and 78 Discussions

In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. For example, the electron configuration of the neon atom is 1s2 2s2 2p6, meaning that the 1s, 2s and 2p subshells are occupied by 2, 2 and 6 electrons respectively.
Electronic configurations describe each electron as moving independently in an orbital, in an average field created by all other orbitals. Mathematically, configurations are described by Slater determinants or configuration state functions.
According to the laws of quantum mechanics, for systems with only one electron, a level of energy is associated with each electron configuration and in certain conditions, electrons are able to move from one configuration to another by the emission or absorption of a quantum of energy, in the form of a photon.
Knowledge of the electron configuration of different atoms is useful in understanding the structure of the periodic table of elements. This is also useful for describing the chemical bonds that hold atoms together. In bulk materials, this same idea helps explain the peculiar properties of lasers and semiconductors.

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  1. P

    I Trying to understand why electrons fill orbitals the way they do

    Ok, I'm a little hesitant to post in the quantum physics forum here because I don't want anyone to make the mistake that I know much about quantum physics :biggrin: But anyways I've been reading some bits lately about electricity and magnetism trying to understand why permanent magnets work the...
  2. PhysicsInterest

    Is there a greater answer for naming D-Block elements the way they do?

    Ok so I’m going into my second year of college and I’m starting to learn more advanced chemistry (pray for me🙏) I’m currently on the topic of D-Block elements and I was already aware of electron configurations and how to write them out… however what I have never come across prior was the use of...
  3. P

    Chemistry: Electron Configurations & Reactivity

    Trying to remember some chemistry here and think I must me remembering something wrong. I'm remembering that the more unpaired electrons in an atom the more reactive it is, or the more bonds it can form. So hydrogen is reactive ie 1 unpaired electron in the 1s orbital. Helium is stable 2 paired...
  4. nomadreid

    Molecular covalent bonds across energy levels

    I am sure this is an elementary question; I'm just trying to clarify some points that were poorly explained to me years ago in secondary school. I know that a full answer would involve solving Schrödinger's equation etc., but keeping this on the level of valence electrons,...) I was confused by...
  5. I

    Chemistry Platinum ion electron configuration

    The answer is [Xe] 4f14 5d8. Why does platinum (and other 6th and 7th period d-block elements) have 4f14 instead of 4f7? Thanks.
  6. rachelmaddiee

    Chemistry Nitrogen: Atomic Number 7 & Electron Configuration

    Nitrogen has an atomic number of 7. Thus, A nitrogen atom has 7 electrons. Nitrogen’s electron configuration is: [He] 2s2 2p3 The nitrogen element has five valence electrons present in 2s and 2p orbitals. So it would have five dots placed around the symbol for nitrogen. Is this correct? I need...
  7. C

    What is the bond order of (Fe2) and (Fe2)+ ?

    From almost writing the complete Molecular orbital electron configuration for ## Fe_2 ## and ## (Fe_2)^+ ## ( I said ' almost ' because I don't know how to write the electronic configuration for the d-bonds ) then I think the bond order for ## Fe_2 ## is 0 and the bond order for ## (Fe_2)^+...
  8. A

    Electron Configuration Question

    There are two kind of electron configuration as I read so far. There are one such as spdf and other such as, for example, 2 8 8 2. What is the name of these electron configurations? What is the difference?
  9. Jimtaff

    I Do we make atoms of Oganneson etc or are they nuclei?

    When the heaviest elements such as element 118 (Oganesson) are created, the production is described as a a collision of an ion projectile (eg calcium-48) with a target atom (eg californium 249). Does this collision result in an atom of oganesson before the decay to 116 (Livermorium) or is it...
  10. yecko

    Electron configuration of Fe(2+)

    Homework Statement Electron configuration of Fe(2+) Homework Equations spdf configuration The Attempt at a Solution 1s2 2s2 2p6 3s2 3p6 3d3 4s2 But from (https://www.thestudentroom.co.uk/showthread.php?t=1232420), it says 1s2 2s2 2p6 3s2 3p6 3d6. isn't electrons fill up 4s shell first...
  11. C

    Showing Consistency with Hund's Rules

    Homework Statement Show that the ground states for the first three elements in the “neon configuration” (Z=11 to 18) are consistent with Hunds rules. Homework Equations From Hyperphysics, the rules are: 1. The term with maximum multiplicity lies lowest in energy 2. For a given multiplicity...
  12. C

    I How can an atom change from ground to excited state?

    I am currently studying a Foundation Program, which includes chemistry. -I can easily understand the distinguishable characteristics between ground and excited state via writing the electron configuration. -But how can an tom changes from ground to excited state ? And can an atom changes from...
  13. V

    Electron Config for Cd2+: Kr 4d10

    Homework Statement Write the electron configuration for Cd 2+. Homework EquationsThe Attempt at a Solution [Kr] 4d10 Whenever we remove electrons do we always remove it from the s orbital in that period. So for cadium ion we remove 5s2 correct? But let's say it's Mn 2+ would we remove the...
  14. nehCrM

    I Electron configuration vs. Lewis dot structure?

    I am trying to make a connection between the two in terms of the electron configuration for an atom relative to the octet rule for Lewis Dot diagrams. Maybe I just don't understand what the electron configuration represents. Why is it that Lewis Dot diagrams utilize 8 valence electrons as a full...
  15. samjohnny

    Electron Configuration of Excited State

    Homework Statement An exercise examining the tin atom (Sn). Tin has a ground state electron configuration of ##[Kr]4d^{10}5s^25p^2##. a) Write down the electronic configuration of the first excited state. b) Illustrate with a vector diagram the allowed total angular momentum ##J## values for...
  16. T

    Electron configuration of the Ni+

    Homework Statement Which is the electron configuration of the Ni+ ion? Homework Equations Ni : [Ar]4s23d8 The Attempt at a Solution Ni+: [Ar]4s13d8 Apparently this solution is wrong and should be Ni+: [Ar]3d9 but I do not know why. As far as I know 4s has less energy than 3d so, why does one...
  17. Metals

    What happens if an atom's electron configuration remains unstable?

    What happens if an atom's electronic configuration remains unstable? So we know atoms react with each other to share or transfer electrons, causing them to bond. It's in their nature to do so; if they do not, they'll remain unstable (apart from some Noble gases which are already stable). What is...
  18. Dong Aleta

    Electron Configuration of Filled Valence Electron Orbitals

    Hi! I have understood how elements such as Be and Ca, with fully filled 2s orbitals, are not to be considered "noble" because they still have unfilled p orbitals. But I'm having trouble understanding how these elements participate in chemical reactions without having any unpaired electrons. My...
  19. H

    Electron Configuration from Term Symbols in Lanthanides

    Hi, I'm new to the forum, and I am very sorry if this has been asked before. I am Japanese and therefore my English might be a little bit awkward. I want to ask about term symbols and if they can be used to derive electron configuration in lanthanides. First of all, I do not major in Physics...
  20. R

    Determining electron configuration with quantum numbers n l

    This relates to a question I asked recently on Quantum Dots, but I'll rephrase it and hopefully any chemists out there can help. If we have (n,l) = (1,2) where n and l are quantum numbers can we determine the orbitals? and hence the number of electrons in a quantum dot? i.e. And also I've...
  21. F

    What is Kr2+ electron configuration?

    I was thinking [Ar] 4s^2, 3d^10, 4p^4 ?
  22. M

    Europiums electron configuration

    I calculated Europium to have a electron configuration of 2 8 18 32 3 and then calculated the chemical formula of Europium Chloride which was EuCl3 which is correct but why is the real electron configuration of Europium 2 8 18 25 8 2 ?
  23. J

    Why isn't chromium's electron configuration 2, 8, 12, 2?

    Its actual electron configuration is 2, 8, 13, 1 even though Vanadium's electron configuration is 2, 8, 11, 2 and Manganese's is 2, 8, 13, 2.
  24. P

    Simple Electron Configuration Question

    I have read from a few sources that an atom's third energy level can sometimes hold 8 electrons, and other times hold 18. In atoms which possesses enough electrons to exceed the the third energy level, what exactly is it that determines the amount of electrons this energy level can hold?
  25. Q

    Electron configuration, magnetism, and unpaired electrons

    My answer key claims it's answer E. I don't think it's right; I think it's cobalt with three unpaired electrons. Not four. A 3d7 configuration, through the Aufbau principle, would fill two of the five d electron pairs completely and leave three half filled. This works mean it's also para...
  26. Z

    Electron Config. for Sg+2: Explained

    Homework Statement For Sg+2 what is the electron configuration. The Attempt at a Solution My immediate response would be [Rn] 7s2, 5f14, 6d2 but the answer is [Rn] is 5f14 6d4 Can someone explain this to me?
  27. B

    Help with electron configuration?

    I don't understand it. I was absent the day it was introduced so I'm behind. I'm trying to learn from google but I can't figure it out. I thought I understood but I guess not. I picked a random element off the periodic table. Gold. I know that's sub level d row 5 column 11 So I thought...
  28. K

    Electron Config: ns2 (n-1)d9 & ns1 np6

    In the "d" orbital of an atom, if it's almost half filled or filled it will get an electron from the nearest "s" orbital to gain a better stability. My question is why not "p" orbital doesn't do such? ns2 (n-1)d9 → ns1 (n-1)d10 ns2 np5 -/→ ns1 np6 ?:cry:
  29. V

    I'm confused about this excited electron configuration

    I have already turned in my homework for chemistry however I'm still confused about this question: Which electron configuration is in an excited state? a.1s2 2s2 2px2 b.1s2 2s1 2px1 2py1 2pz1 My teacher told me that the only choice b was excited because choice a was in violation of Hund's...
  30. D

    Closed electron configuration equivalent to closed shell

    "closed electron configuration" equivalent to "closed shell" Hi, is the term "closed electron configuration" equivalent to "closed shell"? derivator
  31. Y

    Electron Configuration for Multivalent electrons.

    I am trying to draw electron configurations for multivalent electrons for Pb4+ and Pb2+. The work I have: (Xe)6s24f145d10 (PB2+) (Xe)6s04f145d10 (PB4+) the problem I'm having with multivalent structures is: I have no idea which electrons to remove when there is an ionic charge For...
  32. E

    Electron Configuration Exceptions

    This is the electron configuration for Ag (Silver) found on the wikipedia page: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s1 I used the Aufbau Principle and got this instead: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2 4d9 1. I can see that Ag is an exception to the rule, but are there any...
  33. D

    Electron configuration 3d orbitals

    Hello. I'm having a problem understanding the 3d orbitals when I'm doing electron configurations. When you fill up electrons for let's say nickel, Ni, you get the configuration: [Ar]3d8 4s2, if I'm not mistaken. But what I have read, at least I think I have, the 3d orbital gets really...
  34. H

    Chemistry: Electron Configuration of Manganese Cation

    Homework Statement Write the ground state electron configuration of Mn2+. Homework Equations N/A The Attempt at a Solution Well I thought that since it had the 2+ superscript and manganese is a metal, it must have lost two electrons. Manganese has an atomic number of 25 and...
  35. Τ

    Electron Configuration of Platinum

    Homework Statement Why is the electron configuration of neutral Platinum: Pt = [Xe]4f ^{14} 5d ^{9} 6s ^{1} and not?: Pt = [Xe]4f ^{14} 5d ^{10} 6s ^{0} I thought that if the two electrons from the 6s sub-shell were to move to the 5d sub-shell, then 5d sub-shell would be fully...
  36. Τ

    Question on Electron Configuration

    Homework Statement What is the electron configuration for Ti+2? The answer to this question, from my homework, is [Ar]3d2, but I am not able to figure out why. 2. The attempt at a solution I originally thought the configuration was: Ti+2 = [Ar]4s2 and not: Ti+2 = [Ar]3d2 My reasoning was...
  37. N

    Electron Configuration of Uranium

    Homework Statement Electron Configuration of Uranium The Attempt at a Solution [Rn]7s^2 5f^4 But online it says [Rn] 5f^3 6d^1 7s^2 Someone explain why please. Thank you. :)
  38. R

    Relationship between valence electrons and electron configuration

    Why is it that atoms must have 8 valence electrons in order to be stable? Aren't electrons most stable when the orbital is completely filled? Helium's electron configuration is 1s^2, Neon's is 1s^2 2s^2 2p^6, etc. All the noble gases, except for helium, have the p orbital filled. I'm...
  39. B

    Regular chemistry electron configuration help

    Homework Statement Why do transition metals tend to form +1/+2 ions? Take electron configurations into account so that I can better understand this "easy" concept.2. The attempt at a solution I think it has to do with the s orbitals. These, I think are valence electrons that are easily lost...
  40. V

    Find all J values of electron configuration

    Homework Statement Find all permitted J values for electronic configuration 2p3/22 Homework Equations Clebsch-Gordan coefficients maybe ? The Attempt at a Solution Maybe from this ? J = L+S,L+S-1,...,|L-S| Then I first have to find L and S, and just put them in above equation...
  41. P

    Electron Config: Si and O for SiO4

    Homework Statement Write the electron configuration for SiO4. Homework Equations The Attempt at a Solution My professor said we just need to show the configuration for Si and O separately. I think Si gains four electrons, so its configuration is 1s2 2s2 2p6 3s2 3p6 But...
  42. S

    NYC Chemistry Regents Electron Configuration

    Well, I have to find the electron configuration of ions. Relatively simple. But since I don't know how to do it, it's hard. I've seen some past chemistry regents electron configurations and that's too complicated for me. I'm talking about e.c. like 2-8-2. That sort of electron configuration. I...
  43. A

    Why doesn;t Carbon show deviation from electron configuration

    We all know that carbon shows the configuration 1s2- 2s2- 2p2 But, since half-filled and fully filled orbitals are more stable, why doesn't it show the configuration 1s2- 2s1- 2p3 ? Why doesn't the 2s orbital give 1 electron to 2p, as in the case of Chromium, where one electron goes from 3d to...
  44. R

    Electron Configuration - Notation Clarification

    Warm greetings, My confusion surronds Electron-orbitals... My text describes the sub-shells s, p, d, and f. If s shell has 2 electrons in spherical orbit, and p shell 6 electrons in 3 lobed orbitals, where on Earth are the other 2 electrons that complete the orbital shell of Neon? What is...
  45. D

    Doesn't Electron Configuration Prove The Universe Has Three Dimensions

    Is a three dimensional universe not a requirement for electrons to be configured as we know them? Wouldn't atoms at the least have to exist on a three dimensional brane for the electron clouds to exist as they do?
  46. O

    Electron Configuration for Lanthanides

    Homework Statement Explain why ytterbium and europium prefer the 2+ ionic state compare to the rest of the Lanthanides which prefer a 3+ ionic state. The Attempt at a Solution I understand why europium prefers the 2+ ionic state ( largest exchange energy), but when trying to...
  47. A

    The Electron Configuration of Cd2+

    Homework Statement My question is in regards to Cd2+ and its electron configuration. In its neutral state the configuration is [Kr]4d^10 5s^2. What is it in its 2+ state? Homework Equations The Attempt at a Solution The answer is either [Kr] 4d^8 5s^2 or [Kr] 4d^10 5s^0 The...
  48. T

    Cl electron configuration

    Can someone PLEASE explain the electron configuration for Chlorine. I know it is 1s^2, 2s^2, 2p^6, 3s^2, 3p^5 and that the noble gas configuration is [Ne]-3s2-3p5 but what I don't understand is why is it Ne and not Ar since Cl gains one electron 3p^6, that is Ar not Ne, Ne is 1s^2...
  49. S

    Wavefunction and Electron Configuration (Toughy of the Day)

    The wave function for a particular electron is given by: Psi= 4/(9√(4π)) * (6/a)^(3/2) * (r/a)^2 * e^(2i(phi) - (2r)/a) * sin^2 (θ) a) This is an electron in which subshell? b) This is an electron in an atom of which element? c) What is the ionozation energy for this electron, assuming...