Questions tagged [electronic-configuration]

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.

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What do the subscripts 1/2 and 3/2 for the p-orbitals refer to?

What does $p_{1/2}$ and $p_{3/2}$ mean when referring to electron configuration? I've seen sub shells and I'm assuming it has something to do with spin. I am asking this in regard to the $8p_{1/2}$ ...
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A Question on the Role of Triplet Oxygen in the Formation of Artemisinin

It is observed that whereas singlet oxygen is required for an ene reaction with an alkene to give an allyic hydroperoxide, triplet oxygen will react similarly with an enol to give an alpha-hydroperoxy ...
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How come electrons in the d-subshell are considered valence electrons in transition metals?

Similarly, why are f-subshell electrons considered valence electrons in the lanthanides and actinides? I was under the impression that the outermost electrons, and therefore the electrons with the ...
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While filling electrons, we follow Aufbau principle, but not while removing them. Why is this so?

I recently came across a question Why is the vanadium(3+) ion paramagnetic?, where the asker is wondering how $\ce{V^{3+}}$ is paramagnetic (he used Aufbau in reverse to remove the electrons), while ...
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Relative energies of singlet and triplet states in Jablonski diagrams

In a Jablonski diagram, we have singlet and triplet excited states where spin is conserved or changed, respectively. My book says any singlet excited state is found to have higher energy than the ...
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Electron configuration from vanadium to chromium? [duplicate]

The electron configurations for vanadium is: $\ce{1s^2 2s^2 2p^2 3s^2 3p^6 3d^3 4s^2}$, and the electron configuration for chromium is: $\ce{1s^2 2s^2 2p^6 3s^2 3p^6 3d^5 4s^1}$. In looking at the ...
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Exchange of electrons in f orbital

If an f orbital has 6 unpaired electrons then how many electrons can be exchanged. According to me if 2 electrons are added then a half filled f orbital would be formed which is stable (not as much ...
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Electronic configuration of uranium

I read that the electronic configuration of uranium is [Rn] 5f³ 6d¹ 7s² . Given that the subshells fill in the order 5f --> 6d, why is the 5f subshell only partially filled? Why do electrons fill ...
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What's the difference between RHF and UHF?

I am doing a course on electronic structure methods and am somewhat puzzled by the content (I have a physics background). From what I understand Hartree-Fock is a method where you only use the Slater ...
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Difference between change in energy level and hyperfine energy level?

The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom. --> This ...
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Does exotic potassium exist?

I was reading a book called 'Hundred and Seven Stories of Chemistry'. There is a chapter about how the attributes of different elements can change in presence of enormous pressure and temperature. ...
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“NBO diagrams” versus MO diagrams

Molecular orbital diagrams are well known by chemists. According to Wikipedia (emphasis mine), A molecular orbital diagram, or MO diagram, is a qualitative descriptive tool explaining chemical ...
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How P(C2H5)3 acts as a ligand?

How does $\ce{P(C2H5)3}$ acts as a ligand and forms dπ-dπ bonds with transition elements. Why not pπ-dπ bond? I understand that transition elements have d subshell available to accept electrons. ...
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How many d-electrons are in the outer shell of metals like Cadmium (this is counting the 4d electrons)?

First I know similar questions have been asked about counting d-electrons. However, my question is about the electrons in the 4d orbital. For example if I have CdS. The cadmium has a charge of +2. ...
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Why doesn't Sodium (Na) form duplet?

The atomic number of Na is 11 (2, 8, 1). Na loses an electron to achieve octet stability but why can't it just accept an electron to complete duplet stability?
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PAW vs USPP: Pseudopotentials in commercial DFT codes

What is the difference between USPP (ultra-soft pseudopotential) and PAW (projector augmented wave) in commercial DFT codes?
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Degeneracy of second excited state of H-?

This is a question presented in a IIT-JEE 2015 paper I exam. It says, . Not considering the electronic spin, the degeneracy of the second excited state (n = 3) of H atom is 9, while the degeneracy ...
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If the ferric ion is more stable than the ferrous ion, then why is it readily reduced to the latter?

The standard reduction potential value for the ferric ion: \begin{align} \ce{Fe^3+ + e- &<=> Fe^2+} & E^\circ &= \pu{0.77 V} \end{align} The value is positive, hence it means that ...
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Difference between Coupled Cluster and Full CI

I'm looking at some high precision quantum chemistry methods like Coupled Cluster (CC) and FULL CI (FCI). It seems both CC and FCI start from Hartree-Fock and then excite the electron to higher ...
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Which carbon(s) in cyclohexene have the highest electron density?

I think that carbons with highest electron density will be both $\ce C1$ and $\ce C2$ because of the loosely held $\pi$-bond between them, but according to the answer given the carbons with most ...
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Is Zirconium 3+ ion more stable than Zr? [closed]

Is $\ce{Zr^{3+}}$ more stable than the atom, and why if yes?
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Why do rare earth metal oxides vary in color so much?

I only know a little about what causes different color, but I know it has to do with the electron orbitals and how they reflect or absorb/emit incoming light. The rare earth metals are in the ...
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How to tell the needed doping element for semiconductors?

I was reading about a crystal that is a semiconductor, galena. I am confused on how to tell what elements are needed to dope it to make a p or n type semiconductor, as well as how to know which ...
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Why are there 14 electrons in the third shell of iron atom?

The third shell must contain at least 18 electrons. But in iron there are 14 electrons in third and 2 electrons in 4th. Why are there 14 electrons in the third shell of iron atom?
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What is the difference between the quantum numbers of the valence electrons of Carbon and the quantum numbers of Carbon?

Does the question requires something different than finding the correct sets of quantum numbers of C? I'm using the diagram below, and I found that all possibilities fit. why are the unselected ...
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What are complete active space methods and how are such spaces defined for molecules?

I am new to computational chemistry and would like to know about the active space and inactive space terminologies in MCSCF type calculations. For understanding this I have four systems: $\ce{H2O}$ ...
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Aurora borealis - less favored energy transitions higher in atmosphere?

This question describes how some energy transitions become more prominent as you higher in the atmosphere. Short summary: Some electron transitions are "forbidden" by quantum mechanical selection ...
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Why is the iron(II) on the heme molecule depicted as having 6 electrons in its 5 d non- and anti-bonding orbitals?

Approximating the $\ce{Fe}$ complex as a square base pyramid ($D_\mathrm{4h}$ symmetry) with 5 $\ce{N}$ ligands, My electron count of the system gives me 16 electrons – 10 from the $2\times 5$ $\ce{N}$...
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Would singlet oxygen in the engine cause a more efficient combustion?

Today someone told me about a new product — a mesh that is made from 5 different metals and when oxygen passes through it, singlet oxygen appears for a short period of time. This mesh needs to be ...
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How do lone electrons impact the charge of an ion?

This is a quite elementary question, but I still can't wrap my head around it. I know how to calculate the formal charges of an ion or a molecule, but I don't understand what happens when oxygen (...
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Are d electrons ever delocalized in metallic bonding

It has been my understanding that delocalized electrons that participate in metallic bonds come from the highest primary energy level, specifically from the s and p sublevels and that electrons in d ...
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Why might a planar, conjugated molecule be higher in energy than a nonplanar system?

I have a small molecule (23 atoms) for which I want to verify parameters in a molecular mechanics force field. My first step is to look at the potential energy as a function of the dihedral angle, ...
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Finding electron configuration by following the Aufbau principle

In the question, "Electron Configuration of Tellurium", there is mention of the 'follow yellow brick road' method of finding electron configuration. What I'd learned in the past was to find the ...
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How does one find the ground-state term symbol for a configuration that is exactly half-filled?

For instance, the ground-state configuration of N atom is a $p^3$ configuration of all parallel spins and one electron in each $2p$ orbital, which has: Total spin angular momentum, $S = 3 * \frac{1}{...
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Electronic configuration of chromium(II)

Which is the electron configuration for $\ce{Cr^2+}$ (A) $\mathrm{[Ar]4s^23d^4}$ (B) $\mathrm{[Ar]4s^23d^2}$ (C) $\mathrm{[Ar]4s^03d^4}$ (D) $\mathrm{[Ar]4s^43d^2}$ I referred to the ...
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What exactly is the d-orbital splitting and how does this affect the colors for transition metal compounds?

How does d-orbital splitting form colors for transition metals? Why can't the electrons in the d-orbital split for the element Zinc?
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What does “totally reduced” mean?

My textbook mentions that: Iron is unable to be totally reduced... the most common non-zero oxidation states of iron is (o for oxidation, r for reduction) are: +2r, +3, +4o, +5o, +6o. I thought it ...
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1answer
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Does the weird 4s and 3d rule apply for much of the p-block from Ga-Rn?

In the transition metals, $4s$ has a higher energy level than $3d$, because in ionization, the electrons from the $4s$ energy level are lost first. I was thinking that this might be the same for much ...
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Why exactly does atomic radius increase down a group?

I realize this should be a fairly basic question, but I'm still not quite satisfied with what I've been told from numerous sources. The general explanation seems to state that as we go down a group, ...
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Electron configurations for d-block and p-block

Question 1: Why is it that when you get to the transition metals (or the d-block), the energy of the $\ce{3d}$ orbitals becomes slightly less than that of $\ce{4s}$, making $\ce{4s}$ have the ...
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Effects of atmospheric gases on colour of aurora

Recently I moved to the north of Norway, so I've seen quite a few auroras. Because the colour is mainly green, I was sure this must be due to electron transitions in $\ce{N2}$ (because the atmosphere ...
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How to get the condensed electron configuration for Zinc ion

The question said "Write the condensed electron configuration for $\ce{Zn^{2+}}$I got [Ar] 4s$^2+$ 3d$^8$. Why was this the incorrect answer? Zinc lost 2 electrons and surely those electrons should go ...
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How to write electron configuration of Mercury? [duplicate]

I am completely confused about how to write the electron configuration anything higher than Barium because there are so many inconsistencies and misconceptions about the 5d and 4f orbitals. I know ...
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1answer
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how can electrons exchange from 3d orbital to 4s if their energy levels are not equal? [closed]

I was taught that electrons only exchange in orbitals of equal energy or degenerate orbitals. The energy of 3d orbitals is 5 and that of 4s is 4(by n+l rule), but then how is it that in the case of ...
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Why does octet bring stability? [duplicate]

After studying chemical bonding I am stuck at a question that is fundamental to my understanding of chemistry: What is it that makes 8 electrons in the valence shell stable? I googled it and got ...
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How can elements have the same number of electrons, but different electron configurations? [duplicate]

$\ce{Ti}$ and $\ce{Cr^2+}$ are isoelectronic, yet their electron configurations are different, with the former's being $\ce{[Ar] 4s^2 3d^2}$ and the latter's being $\ce{[Ar] 3d^4}$. How can that be ...
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What is the physical basis for Hund's first rule?

According to Hund's first rule, a set of degenerate orbitals are singly occupied first, before the second slot in any of the orbitals are populated. This is quite intuitive because electron-electron ...
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2answers
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How to distinguish first excited state and second excited state?

I am learning excited state calculation. In this paper, the author use "$D_0$","$D_1$" represent excited state of nitrate radical. I know the symbol such as "$D_1$","$T_2$" means first excited ...
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What do these labels for molecular electronic states mean?

What do these symbols mean in excited states? $${}^2\!A_2,{}^2\!B_1,{}^4\!A''$$ I am confused with these representations, found in the abstract of this paper. I think it is kind of a representation ...
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Causes for the irregular electron configuration of the lanthanides

I know what the electron configurations of the lanthanides are, but I was asking myself, why they are so irregular. The configutation of Lanthanum is $\mathrm{5d^1\ 6s^2}$, but according to the ...

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