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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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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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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Why are covalent bonds formed? [duplicate]

As far as I know, -covalent bonds are formed because atoms are unstable -unfilled valence electrons -want to fill up their outer rings and become stable BUT, why does compounds like ClF3 exist? Why ...
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Is there a difference between energy levels and electron shells?

Is there any difference between energy levels and electron shells, or do they mean the same thing? Does the number of energy levels remain constant when progressing across a period?
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Formation of complexes by ferric ions is more frequent than ferrous ions. Why?

Looking at the electronic configurations of ferrous and ferric ions they are d6 and d5 systems respectively. Hence, ferric ions are more stable. But in octahedral complexes like hexathiocyanates, the ...
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The Hund's Rule [duplicate]

According to hund's rule, electrons must occupy singularly first in the orbitals before pairing up. And if not, the atom would not be stable. Imagine if there are electrons that do not obey Hund's ...
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Electronic configuration and the periodic table

I came across the following question: If each orbital can hold a max. of 3 e– what is the number of elements in the 4th period of the periodic table? I was unable to even start the thought ...
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Computational methods to obtain relative energies of electronic configurations of atoms

When one learns the Aufbau principle to “predict” electronic configurations, and the $(n + \ell)$ ordering rule (or Madelung rule), one also learns of the exceptions to the rules… some of which (Cr, ...
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What is the number of unpaired electrons in Fe 2+? [closed]

Specifically, how can I find out the number of unpaired electrons in any ion?
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In Chemistry, is it possible to use the old representation of the atom as a nucleus surrounded by orbiting particles?

In Physics, Newton's laws are enough for many applications. Sometimes, relativity must be used instead or complementary, and sometimes, Quantum Mechanics. Is this the same case with Chemistry? Are ...
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What is pairing energy of electrons?

What exactly is pairing energy when electrons are paired in orbitals and what is responsible for it.
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Can orbitals in atoms be compressed?

Consider an atom (carbon) with a ground state valence electron configuration of: $$ \underset{3s}{[\uparrow \downarrow]} \underset{3p}{[\uparrow \vert \uparrow \vert \; \; ]} $$ In some molecules ...
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Why do atoms need 8 electrons to stabilize? [duplicate]

As the title says. I have surfed all of the net but could never find the answer to this question. Why do atoms need 8 electrons to stabilize? I mean why not 7 or 5 or 10 electrons? Why specifically 8? ...
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Howcome orbitals become 'core-like' when electrons are removed?

It seems to me that f-orbitals for lanthanide metals are treated as 'core-like' when a certain number of electrons have been removed. Or, as Radiochemistry puts it, The 4f binding energy is so ...
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Why don't we see these lanthanide species?

For most lanthanide metals$^{[1]}$, the stable oxidation state is III. The general electronic structure$^{[2]}$ is $$\ce{[Xe] 4f^{0}^{-14} 5s^2 5p^6 5d^{0}^{-1} 6s^2}.$$ Elements that have the d-...
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Predominance of III oxidation state for lanthanides [closed]

For most lanthanide metals, the stable oxidation state is III [*]. The general electronic structure is $$\ce{[Xe] 4f^{0}^{-14} 5s^2 5p^6 5d^{0}^{-1} 6s^2}\ \ [**].$$ Elements that have the d-electron ...
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What intrinsic property do metals have that causes their delocalisation?

So I understand that electrons in metals delocalise completely and are free to move around. But my question is, why would something like Nitrogen not delocalise, whereas say Iron or Bismuth does? What ...
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Clarification on absorption spectra and crystal field theory

My textbook, Chemistry: The Central Science, gives this figure to explain the purple color of the hexaaquatitanium(III) ion: Such absorption spectra are common to chemistry and biochemistry. However, ...
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Why isn't 4s1 electron of Chromium the last electron?

I know that to aid the symmetry of singly occupied orbitals one electron jumps from 4s orbital to 3d orbital thus giving Chromium the configuration 3d5 4s1. But my question is, when we're evaluating ...
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Molecular term symbols for excited state oxygen

What are the possible term symbols for excited state oxygen with configuration $(1\pi_u)^3$,$(1\pi^*_g)^3$ (all other occupied orbitals are closed shell)? Based on the possible values of S and $\...
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Transition metals have a half filled s band in their metallic states

I was reading this "Chemical bonding at surfaces and interfaces" book. Here in page 69, they argued that interactions of transition metals to s band of adsorbate would be same because transition ...
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Table of expanded electronic structures of atoms

Where can I find the table containing expanded electronic configurations for atoms in the periodic table, showing how outer electrons are distributed between different atomic orbitals? I really just ...
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Why does electron configuration in the periodic table is different when you follow the aufbau principle? [duplicate]

. In periodic table for example Ag has an electron configuration of [Kr] 4d10,5s1 but when you do it yourself using Aufbau principle it should be [Kr] 5s2 4d9. Why is that? When ask for Ag + valence ...
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Hund's rules for Li, contradiction?

Hund's rules basically state that we sould maxiumise $S$ and for a given value of $S$ maximise $L$. So let us take the case of Li. Li has 3 electrons, clearly the first 2 are in the $n=1$ state, with $...
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Why does Boron only need 6 valence electrons unlike the standard 8?

So I was a bit confused. Hydrogen and Boron seem to be the only outliers to the octet rule. Hydrogen makes sense because it has only one shell and 2 electrons complete its shell. Boron's configuration,...
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Are there any strategies to determine bond order and hybridization rankings without drawing the Lewis Structure?

I'm not Chemist. I'm taking a chemistry class in college, and the test review contains many questions where I'm asked to rank from least to greatest based on bond order, polarity, and bond angles. I ...
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How many electrons are around the platinum in an ethenetriplatinate complex?

In $\ce{[Pt3(C2H4)]-}$, how many electrons are there around platinum? While solving this problem I thought three $\ce{Pt}$ formed a triangle with ethylene above. But I was confused about how the $\ce{...
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Band alignment of heterojunctions

I have seen several band bending diagrams in journals and the web. However, I am not sure as to how they align them. Some diagram appear to align the vacuum level and some align them by Fermi Level. I ...
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Why is this a Lewis structure of ethyl acetate?

I read somewhere that the structure in the following picture is a Lewis structure of ethyl acetate. However, I don't understand why: The $\ce{C}$ has a positive charge, but only three bonds The $\...
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The stability of the cupric and cuprous ions [duplicate]

My teacher told me that $\ce{Cu^2+}$ is more stable than $\ce{Cu+}$ in solution, but why? I think $\ce{Cu+}$ is $\ce{[Ar] 3d^10 }$ ,$\ce{Cu^2+}$ is $\ce{[Ar] 3d^9}$, why is $\ce{Cu^2+}$ more stable ...
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How many d-electrons are in the outer shell of the metals in following compounds: [duplicate]

How many d-electrons are in the outer shell of the metals in following compounds: ZnS Do I just use Zn^2+ and as I know that in Ions the s orbitals are removed first I count 10 d electrons? However ...
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How many d-eletrons are in the outer shell of following compounds:

How many d-electrons are in the outer shell of the metals in following compounds: $\ce{ZnS}$ and $\ce{NiS}$ So sulphur does not has any $\ce{d}$ electrons and $\ce{Zn}$ has $10\ce{d}$ electrons. ...
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Why is the 5d orbital instead of the 4f orbital filled in lanthanum?

For orbitals with the same value of $n + l$ (e.g. the $\mathrm{3d}$ and $\mathrm{4p}$ orbitals), we usually expect the orbital with the lower value of $n$ to be filled earlier. Hence, for example, the ...
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What is a electronic configuration of scandium ion? [closed]

The electronic configuration of Scandium is: $\ce{[Ar] 4s^2 3d^1}$ What is the electronic configuration of Scandium ion? Also about the electronic configuration of Cobalt, which is $\ce{[Ar] 4s^2 3d^...
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Are there no d-electrons in calcium?

For calcium, the electron configuration is $\mathrm{1s^2\:2s^2\:2p^6\:3s^2\:3p^6\:4s^2}$. Does it mean there's no electron in d sub-shell? Also, how would one write the electron configuration for a ...
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Line spectrum of boron

I'm having trouble with this question from a first year undergraduate chemistry paper. The question states How many lines will appear in the line spectrum of the Boron atom if the valence electron in ...
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Electronic configuration of excited states of iron

The electron configuration of the ground state of $\ce{Fe}$ is $\mathrm{1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6}$. What are the configurations of its first and third excited states? The first excited ...
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Why doesn't tetrachloridotitanate(II) obey the 18-electron rule?

I have worked out that the complex comes to 10 electrons, however I do not understand why it does not obey the 18-electron rule? What are the factors that account for this?
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What is the correct order of subshell energies? [duplicate]

I was taught in high school that the order is given by the Aufbau Principle: 1s>2s>2p>3s>3p>4s>3d>4p>5s>4d>5p>6s>4f>5d>6p... Why is the 3d subshell higher in energy than the 4s subshell if it is in a ...
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Electron orbital diagram of vanadium [duplicate]

I am learning about electron configurations and I came across the "exceptions" of $\ce{Cr}$ and $\ce{Cu}$ where electrons actually half fill the $\mathrm d$ orbitals instead of the expected $\mathrm s$...
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Why ground-state configuration is consistent (“additive”) from one element to the next?

Ground-state configuration ("electron shells") is consistent throughout the periodic table, for example: (source) Why is it this way if the Hamiltonian of each atom is different? In other words, why ...
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Where can I find a collection of density functional parameterizations?

I want to implement a solution to the electronic Schroedinger equation using DFT. I know there are many, many functionals to choose from but don't know where to start. I'd like to start with a couple ...
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Orbitals and Pauli Exclusion Principle without Slater determinants

I'm trying to understand how to apply the pauli exclusion principle to the Born-Oppenheimer approximation of molecular structure. Let me preface this by saying I'm not a chemist nor physicist. I'm a ...
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Why does mercury in mercuric acetate have a lone pair?

The configuration of mercury ends with $6s^{2}$. In mercuric acetate, mercury is in the +2 oxidation state, so does it still have a lone pair?
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Anomalous Electronic Configuration of Thorium

The electronic configuration of thorium ($Z=90$) is $5\mathrm f^0 6\mathrm d^2 7\mathrm s^2$. But, according to the aufbau principle, the electrons should first enter the $\mathrm f$ subshell and not ...
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What is the electronic configuration of Cr (+1) ion

I believe it should be $\ce{d^5}$ , but i found out that it is $\ce{d^4s^1}$. Is it so? I have not found any explanation for the following. So why the strange configuration?
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Tungsten 4+ ion magnetism?

I just had a quiz and struggled on a particular question: Tungsten forms a $+4$ ion. It is observed to be diamagnetic. The electron configuration for this ion may not be what you would expect. ...

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