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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Do diatomic isoelectronic molecules have the same bond order even when the octet rule is not followed?

It can be observed and proven that diatomic isoelectronic molecules have the same bond order when they follow the octet rule (upto 3rd period elements). But what about when they do not follow the ...
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Why is it wrong to draw the Lewis structure of a molecule's atoms and then figure out the Lewis structure of that molecule

When drawing for example the Lewis structure of nitrate ion (NO3)^-1 whould it be wrong to draw nitrogen and oxygen separately and then try to figure out the structure of the ion? In that case does ...
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How do the spin-matrices change in systems without spherical symmetry?

The (non-relativistic) spin matrices of a free electron, with $z$ as the quantization axis, read: $$ \boldsymbol{S}_{x}=\frac{\hbar}{2}\left[\begin{array}{ll} 0 & 1 \\ 1 & 0 \end{array}\right],...
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How to obtain excited state energies from configuration interaction? (Helium example)

A theory of CI method For going beyond the Hartree–Fock (one determinant) approximation one introduce configuration interaction (CI). Interaction means the mixing (interaction) of different electronic ...
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Hund's Rule for Determining Term Symbol Energy Order

In order to determine the energy order based on J-value for term symbols we employ Hund's rule: In a less than $\frac12$-filled subshell Lowest J-value is Lowest energy In a more than $\frac12$-...
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Why electron moves into 3d orbital after filling of 3p orbital during the excitation of Sulphur and some other elements? [duplicate]

Why electron moves into 3d orbital after filling of 3p orbital during the excitation of Sulphur and some other elements? Why do not it move into 4s orbital after filling of 3p orbital ? I have read ...
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Electronic vibrational rotational transition of electrons -- for a transition from $\Sigma$ to $\Pi$ how are P and R branches possible?

Suppose we have a diatomic molecule in a $^1\Sigma$ state, and it transitions to an excited $^1\Pi$ state. Note that the total spin of the electrons remains unchanged ($\Delta S=0$) as we can assume ...
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How to use a Nafion sheet Proton Exchange Membrane PEM

I am trying to use a Nafion PEM in a fuel cell configuration. Previously, I was taught to drop a little bit of Nafion solution on the membrane and heat press it between the electrodes. Why do we need ...
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Can there be a molecule where every atom is covalently bonded to every other atom? [closed]

I was wondering if muliple atoms could bond in a ring, but share a pair of electrons with every other atom in the molecule so that every atom is connected to every other atom. Would it be possible for ...
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A question regarding excitation of electrons in atomic orbital [closed]

In Bohr's model of an atom, the formula used to find the energy between the 2 orbits and wavelength of emitted photon was valid only for single electron species like hydrogen.In the case of a multi-...
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Can halogens show -3 or -5 or -7 oxidation state. Why? [closed]

I mean can we think it like if the electrons get excited into the d orbitals and because there are now more than one unpaired electron, why does it only loose them and why don't they accept more than ...
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In Lanthanides, Why is electron removed from 4f before 5p? [duplicate]

I've been taught that electrons are removed first from valence shell electrons with highest energy. But In Lanthanides, for example taking configuration- [Xe]4f⁴6s², If we go to +3 Oxidation State, ...
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Exceptional electronic configuration of Chromium

I understand that the reason for the exceptional electronic configuration of Cr is the increased stability of half filled set of orbitals But here's an excerpt from my textbook …consider the case of ...
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Notation for orbital coefficient matrix in RHF vs UHF

My question stems from Table 1 of this paper: "Generalized Hartree–Fock Description of Molecular Dissociation, by Carlos A. Jiménez-Hoyos, Thomas M. Henderson, and Gustavo E. Scuseria" https:...
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Application of Hund's third rule to rhodium

The rhodium atom has electronic configuration: $[\ce{Kr}] \,\mathrm{4d^8\,5s^1}$; the atomic term symbol is $^4F$. The possible $j$-values are $9/2$, $7/2$, $5/2$ and $3/2$. However, when using Hund's ...
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Why are higher-energy orbitals larger in size/radius?

I know the different atomic orbitals of atoms are derived from the wave function in the Schroedinger equation. Because I'm not a mathematician, though, I can't decipher the Schroedinger equation and ...
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Equation describing electrons in a atom/ion [closed]

When not only 1 electron exist in the atom/ion the electrons of the atom/ion interact with each other and with the nucleus. Do we solve this equations: or this equation? x is the position of a ...
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How do we write spin multiplicity for Mn(2+), Mn(7+)?

Mn has atomic number = 25 Since it is an exception to electronic configuration , unlike having = $\mathrm{3d^7}$ , it has electronic configuration = $\mathrm{3d^5,4s^2}$. Formula for spin multiplicity ...
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Exploiting 8-fold symmetry of ERI tensor for building Coulomb and Exchange matrices

I'm trying to write a restricted Hartree Fock code in Fortran that reads in a file of zeroth-iteration 1 and 2 electron integrals (FCIDUMP format) and uses them to do the SCF procedure from an initial ...
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Physical origin of induction and dispersion energies

I am reading this book on non-covalent interactions. Chapter 1 states that there are 3 types of non-covalent interactions: Electrostatic interactions, which are just the coulomb interactions between ...
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Why is the distribution of electrons of calcium in K,L,M,N shells 2,8,8,2 instead of 2,8,9,1?

I'm a beginner to this topic, so this would likely sound dumb. As far as I know, when distributing electrons in energy shells, the last energy shell can't have more than 8 electrons. So for calcium, ...
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Reasoning for why anions have larger radius

I understand one thread of logic that adding electrons to create an anion creates more electron repulsion hence increasing the ionic radius. What's wrong with the reasoning that there is now a larger ...
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Is configuration interaction able to produce degenerate ground states?

I am new to multi-determinant theories. What motivates me in asking this question is the following observation: Consider the Dyson orbital of a $\ce{CO2}$ molecule whose axis is parallel to the $z$ ...
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Experimental evidence for anomalous electronic configurations of chromium and copper

Chromium ($\mathrm{3d^5\,4s^1}$) and copper ($\mathrm{3d^{10}\,4s^1}$) are fairly well-known exceptions to the aufbau principle, often attributed to the stability of the half- or fully-filled 3d ...
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Why SCF procedure in Hartree-Fock doesn't keep returning the same coefficients?

In the context of Hartree-Fock theory, using Roothaan formalism, we write: FC=SCE where F is the matrix of the Fock operator, C are the coefficients to be used in the construction of the wave function ...
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Electronic configuration of excited states

Fill the following table: $$ \begin{array}{lccr} \hline \text{Electronic configuration} & \text{Term} & J & E/\pu{cm^-1} \\ \hline [\ce{Ne}]\mathrm{(3s)^2(3p)^5} & & &...
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Can the electronic configurations give any information about the actual structure of the atom?

The zeroth order wavefunction for an He atom in the ground state is $\psi^0_\text{He}=\psi_{1s}(1)\psi_{1s}(2)$ and hence the electronic configuration $1s^2$. But then we start making purterbations, ...
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How does the electronic structure Hamiltonian scales with basis sets and the number electrons?

Given a chemical system with $N$ electrons and a basis set $S = \{\phi_i\}$ with $K$ basis functions. If one to discretize the Hamiltonian with this basis sets, what is the dimension? The electronic ...
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How can I formally justify the description of an electronic excitation that includes only the relevant orbitals?

I am writing a small program to animate electronic transitions. To do this, I am animating a Rabi cycle for a single electron as it moves from an occupied into a virtual orbital. The on-resonance ...
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Why electron configuration of thulium is $[\ce{Xe}]~\mathrm{(6s)^2(4f)^{13}}$ instead of$[\ce{Xe}]~\mathrm{(6s)^1(4f)^{14}}$?

We know that half-filled or full filled orbitals are more stable. That's why the ground state electron configuration of gadolinium is $[\ce{Xe}]~\mathrm{(6s)^2(4f)^7(5d)^1}$ rather than$[\ce{Xe}]~\...
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What does valence electron mean (in the context of spdf orbitals)?

For a little bit of context, my background is in physics and my understanding of chemistry doesn't go past, say, middle school level. Recently, I decided to self-study chemistry and picked up "...
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Do Ions with less stability have less energy of ionization than those who are stable?

Problem. I've come up with the strange example of the third energy of ionization of both $\pu{Mg}$ and $\pu{Al}$, the standard logic that is to be applied on any problem of "which element has ...
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How can I understand if my system has degenerate electronic configuration?

How can I understand if my system has degenerate electronic configuration? I'm running some post-HF methods and in the meanwhile try to understand which is the most accurate method for my system. ...
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2 answers
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Why does/doesn't sodium carbide exist?

(Here, I quote a question from an Indonesian undergraduate Chemistry competition: "sodium carbide reacts with water to form ethyne gas." This is the problem that caused me to ask this ...
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4 answers
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Can a metal be forced to form an anion theoretically? [duplicate]

I know that metals have the capability to lose electrons and form cations, but is it also theoretically possible to supply an electron to a metal so that it forms an anion? If so, has it ever been ...
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How is electron richness defined?

What does it mean for an atom/molecule to be electron rich? For instance, why is the methyl carbanion considered electron rich (having excess electrons) even though it has a complete octet, no more, ...
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2 votes
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Total orbital angular momentum in a filled p subshell

From "Physical Chemistry", P. Atkins, J. De Paula, 9th edition, page 358 "A closed shell has zero orbital angular momentum because all the individual orbital angular momenta sum to ...
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Electronic Configuration and Octave Rule [closed]

According to Octave rule, a shell cannot hold more than 8 electrons But according to atomic orbitals, The maximum number of electrons in the shell with principal quantum number ...
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Why does increasing subshell cause ionization energy to decrease?

I know that increasing subshell decreases ionization energy; for example, going from Beryllium to Boron. I do not understand why this is. The answer my textbook (Chemistry 2e on OpenStax) gives is ...
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The ways to determine if an ionic compound is paramagnetic or not

Find which of $\ce{Na2O2}$ and $\ce{CsO2}$ is paramagnetic. (Adapted from JEE advanced paper-1 2016, q.22) The given solution involves removing the cations and taking the anionic part, i.e. $\ce{O2^2-...
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11 votes
2 answers
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Why are protons more common than hydride ion?

I'm a high school student. I noticed $\ce{H+}$ ion is commonly present in my books while I didn't find any presence of $\ce{H-}$ ions in my books. However, I found on internet that $\ce{H-}$ also ...
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Do covalent bonds fit in with the orbital theory of atomic structure?

Which atomic model do covalent bonds adhere to? In the the covalent bond between $2$ oxygen atoms, we consider each oxygen atom to have $6$ valence electrons, thus resulting in a double covalent bond. ...
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Can molecular systems display negative magnetic susceptibility of a higher magnitude than bismuth?

Bismuth has the biggest value when it comes to a negative magnetic susceptibility than all other elements, ignoring superconductors, as they would have a value of -1. Yet, when tables displaying ...
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Are there any ways of modifying molecules to increase their probability of two photon absorption?

While checking two photon microscopy, the use of high flux femtosecond laser is required for the dual absorption of photons, due to the low probability of these two photons being absorbed. Is there ...
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The ambiguity regarding aufbau principle

According to a Blog https://ericscerri.blogspot.com/2012/06/trouble-with-using-aufbau-to-find.html written by Dr.Eric Scerri, On moving from the $\ce{Sc^3+}$ ion to that of $\ce{Sc^2+}$ it is plain ...
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5 votes
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How can a hydrogen atom ever emit an X-ray photon?

From Scientific American, February 2014: The Proton Radius Puzzle: ...we had to tune the laser so that it came in with exactly the right amount of energy. The atom would make the jump to the higher ...
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What is the average distance between electron 'shells' in an atom? Or between the innermost shell and the nucleus? [closed]

Somehow, I've never come across any mention of the actual, physical distances between, say the 1s and 2s shells in an atom, whether large or small.... I know that p, d and f (and g?) shells are oddly ...
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How to compare magnetic moment of chromium(III) and cobalt(II) ions?

Is there any way of comparing the magnetic moments of $\ce{Co^2+}$ and $\ce{Cr^3+}$ gas phase ions by just going through their electronic configuration?Or is it just experimental data?
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3 votes
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What happens to the 2s orbital in carbon-hydrogen bonds? [closed]

I was taught in high school that carbon atoms by themselves are capable of establishing covalent bonds with with as far as four hydrogens atoms. Nowadays, trying to understand the topic in-depth, I ...
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6 votes
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Why is potassium less dense than sodium?

Potassium has a density of $\pu{0.86g/cm3}$ and sodium has a density of $\pu{0.97g/cm3}$,even though potassium is below sodium and one might expect the alkali metals to exhibit monotonously increasing ...
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