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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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4 votes
2 answers
3k views

Why do halogens have odd numbers as oxidation number?

Halogens like $\ce{Cl}$ always exhibit $+7,+5,+3,+1,-1$ as their oxidation numbers. I found the following answer after checking several sources: Halogen atoms have $7$ electrons in their valence ...
8 votes
0 answers
4k views

Why does iron have an abnormally high ionization energy?

Along a period the ionization energy should increase because the atomic number is increasing, but there is negligible increase in shielding. However, $\mathrm{IE}_\ce{Mn} < \mathrm{IE}_\ce{Fe} > ...
-4 votes
1 answer
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Explanation of metallic crystal structures using orbitals and electron configuration

There has to be a direct relation between metallic crystal structure formation and electrons in orbitals. For instance, we know that Fe2+ forms body centered cubic or bcc structure with the ...
-3 votes
1 answer
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Question from J. D. Lee about Quantum Numbers

There's this question in J. D. Lee: Concise Inorganic Chemistry, which I haven't understood exactly. Which of the following may have the same set of quantum numbers? The last electron of scandium and ...
0 votes
2 answers
116 views

What does "predicted" mean in an electronic configuration?

I've noticed the term "(predicted)" appearing at the end of electron configurations for heavier elements. Could you explain what it signifies and the reason behind it? I haven't been able to ...
5 votes
3 answers
385 views

Can orbitals in atoms be compressed?

Consider an atom (carbon) with a ground state valence electron configuration of: $$ \underset{2s}{[\uparrow \downarrow]} \underset{2p}{[\uparrow \vert \uparrow \vert \; \; ]} $$ In some molecules such ...
8 votes
1 answer
1k views

Why is nitrogen dioxide brown?

Nitrogen dioxide (NO2) is a reddish brown molecule, while its dimer nitrogen tetroxide (N2O4) is colorless. Can you give a reasonably detailed explanation for this from electronic structure theory? ...
1 vote
1 answer
230 views

Why the electronic configuration of samarium is ending with 4f⁶6s²

What is coming in my mind is that 4f^7 6s^1 should be more stable as it allows two orbitals to be half filled rather than 4f^6 6s^2 in which only one orbital is completely filled....can someone please ...
4 votes
4 answers
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Could someone please explain the difference between m/z and m/e in mass spectroscopy

The definition: The abbreviation m/z is used to denote the dimensionless quantity formed by dividing the mass number of an ion by its charge number. It has long been called the mass-to-charge ratio ...
2 votes
0 answers
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How is the electronic configuration of elements determined practically? [duplicate]

How is the electronic configuration of elements determined in practical? Theoretically, we use certain rules (Aufbau principle, Pauli exclusion principle, and Hund's rule) to define the electronic ...
-3 votes
2 answers
73 views

Electronic Configuration of Atomic Numbers 20-28 and 29 (Calcium - Nickel) and Copper [closed]

I have always been confused as to why elements of atomic numbers 20-28, i.e., Calcium to Nickel have 2 valence electrons in their outer shell. Starting from Potassium, why is one electron present in ...
1 vote
1 answer
80 views

Does ionisation change the physical/chemical properties of an atom?

From what I have learned, the number of electrons on the outermost shell (called the valence electrons), determines the chemical properties of an atom, this is why elements in the same group have ...
31 votes
3 answers
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Why does the 3rd electron shell start filling up with scandium?

The electron configuration of calcium is 2, 8, 8, 2, where up to that point each shell, asides from the first shell counts up to 8 - why then does scandium have an electron configuration of 2, 8, 9, 2?...
3 votes
1 answer
69 views

Why are Mo(NR2)3 complexes isolobal with the nitrogen atom in N2

In a Molybdenum complex of the form Mo(NR2)3, the Mo is in the oxidation state of +3, leaving it with 3 d electrons. When combined with an additional 2*3 electrons from the ligands, this leaves it ...
1 vote
0 answers
120 views

Cation/Anion UV-Vis absorption

I want to understand how the ground state absorption of a molecule shifts if an electron is added or removed. I found these two publications 1 and 2 that observe shifts, but both times a redshift, be ...
1 vote
1 answer
105 views

How did scientists prove that electron configuration was true if we do not know exactly where electrons are? [closed]

In Wikipedia, there is an entry for electron configurations which explains all about them, but I did not find from this article how they were discovered. If we take into account Schrodinger's quantum ...
4 votes
1 answer
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Correct Electron Configuration of Ni-28

I have seen two electron configurations for $\ce{_{28}Ni}$ in my chemistry textbook: $$[\ce{Ar}]~3d^8~4s^2$$ $$[\ce{Ar}]~3d^9~4s^1$$ Which of those is actually the correct one (in reality)? Why ...
0 votes
0 answers
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Jahn-Teller Distortion: How to compare magnitudes (in Cu2+ complexes)?

Octahedral complex of copper(II) undergo structural distortion (Jahn-Teller). Which one of the given copper(II) complexes will who the maximum structural distortion? (en - ethylenediamine) (A) $[Cu(...
0 votes
1 answer
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Calculate the valence of Fe2O3 [duplicate]

$$\ce{FeO}$$ Is called "Iron(II) oxide ". $$\ce{Fe_2O_3}$$ Is called "Iron(III) oxide ". The number in the parenthesis is "Valence" of the substance. Frankly, I don't know how to calculate such ...
1 vote
2 answers
11k views

Calculating valence of oxides

Learning about oxides. Basically when oxygen is combined with a metal. $$\ce{FeO}$$ This is called "iron oxide (II)" according to my book. Apparently, the II represents the valence. But how ...
8 votes
3 answers
27k views

How to get the valencies of elements?

How to find the valencies of elements by using its distribution of electrons? Please explain the method in simple words. Do you have to study the valencies or is there a simple way of remembering? PS:...
2 votes
1 answer
298 views

Strange valence numbers? [duplicate]

I'm trying to understand why ChemReference sometimes lists the valence electrons as a number I don't expect. Take oxygen, for instance. It should have six valence electrons, however the site lists two....
0 votes
1 answer
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Non-octet structures of stable nitrogen compounds

A question in my exercise book demonstrates that nitrogen cannot form non-octet structures since the most common examples — nitrogen dioxide and nitrogen monoxide — are unstable/reactive. For example, ...
6 votes
1 answer
263 views

where could I find the standard atomic orbital energy of all elements?

I am trying to find the standard atomic orbital energy of all elements. Here is the data I found in some old books: I am looking for some more modernized data, I tried to look for the data in the CRC ...
0 votes
0 answers
185 views

Radius of Ag+ and K+

According to the database of ionic radius Database of ionic radius The ionic radius of silver(I) cation is totally smaller than potassium(I), regardless of their coordination number. It seems quite ...
0 votes
0 answers
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When relaxing the strong field interaction, the (t2g)^2 configuration splits into 4 states. What is the symbolic configuration of the Eg state?

When relaxing the infinitely strong field, the electrons start to feel one another's presence. They will, therefore, give rise to sets of states such as T1g, T2g... for the (t2g)^2 initial ...
2 votes
3 answers
16k views

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 ...
4 votes
1 answer
271 views

Eigenfunctions of total angular momenta as linear combinations of Slater-determinants

In the Hartree scheme for many-electron atoms, the approximated Hamiltonian (in a.u.) $$\hat{H} = \sum_{i=1}^Z \left(-\frac{1}{2} \nabla_i^2 -\frac{Z}{r_i} + V_\text{H}\left(r_i\right)\right)$$ is ...
6 votes
3 answers
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Why are there so many metals in the periodic table?

Brief Background: I was studying about the 'classical electronic configuration' of the first 20 elements of the periodic table today and was bewildered by the fact that there are an equal number of ...
0 votes
3 answers
431 views

How can a methyl cation exist without 8 valence electrons?

So far I have been taught that everything wants to achieve noble gas configuration - 8 electrons in the outer shell. I came across a methyl cation. Which contains a positive carbon, no lone pairs and ...
5 votes
1 answer
1k views

What is the correct electronic configuration of darmstadtium?

Some of the places, the electronic configuration of darmstadtium ($\ce{Ds}$) is given as $\mathrm{6d^9 7s^1}$ while at some other places, it is $\mathrm{6d^8 7s^2}$. Which among the two is correct?
1 vote
1 answer
1k views

What determines the higher priority in CIP rules, if both groups have the same atoms?

Which of the following groups has the highest priority in the Cahn-Ingold-Prelog sequence rules? a) CH2CH3 b) CH=CH2 c) C≡CH d) C(CH3)3 I narrowed it down to either C or D. The carbon in answer C is ...
-1 votes
1 answer
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Convergence limit of emission spectra for atoms with multiple electrons

In high school chemistry, students are taught that the convergence limit in the emission spectrum of an element can be used to determine the first ionization energy. However, what about the second, ...
4 votes
1 answer
274 views

Principal quantum number and 'good' quantum numbers

When we discuss about configurations we specify n, l, m quantum numbers for the individual electrons. My question is: why when we pass from configurations to atomic terms in order to use the total ...
4 votes
2 answers
5k views

Why Fe 3+ is more common than Fe 2+

I heard that $\ce{Fe}(\mathrm{III})$ is more common than $\ce{Fe}(\mathrm{II})$ but I've not heard a very clear explanation. Could someone please explain this incorporating electron configurations in ...
-1 votes
1 answer
547 views

Why is iron(III) more stable than iron(II)?

What I have seen, and what has been answered before (Why Fe 3+ is more common than Fe 2+), is that it is due to the half filled d orbital of $\ce{Fe^3+}$ compared to $\ce{Fe^2+}$. I don't understand ...
6 votes
0 answers
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Predominance of III oxidation state for lanthanides

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 ...
-2 votes
1 answer
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D block elements and the cation of cobalt [closed]

The configuration of cobalt in its ground state is $\ce{[Ar] 4s^2 3d^7}$. when it loses 2 electrons, it supposedly leaves from s orbital making it $\ce{[Ar] 4s^0 3d^7}$. But since the s and d orbital ...
-2 votes
3 answers
163 views

Why is there a non-uniformity in even the reasons that explain exceptions in the trends in chemistry? [closed]

I have been studying the periodic table and several properties of atoms like the Ionization Energy, Atomic Radii, Electron gain enthalpy, Electronegativity etc. Now, each property has somewhat of a &...
3 votes
2 answers
336 views

Does the triplet sigma state of a diatomic molecule experience spin-orbit coupling?

I know that states with spin S=0 in a diatomic molecule have no spin orbit coupling, independent on the value of the projection of the total electronic angular momentum. I expect the same is true if ...
7 votes
1 answer
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Why is Thorium (At. no. 90) an f-block element at all?

Being an exception of the Aufbau principle, Thorium has an electronic configuration of $\ce{[Rn]}\mathrm{7s^25f^06d^2}$ instead of the expected $\ce{[Rn]}\mathrm{7s^2 5f^2 6d^0}$. Two other elements, ...
7 votes
1 answer
134 views

Confusion about the number of microstates for orbitals

I am very confused about the microstates for a specific orbital. Let's suppose I have an electronic configuration $$ \ce{[\dots] 2p^5} $$ Considering the symmetry of the orbitals and the "...
4 votes
1 answer
230 views

Why does berkelium have two electronic configurations?

J.D. Lee Concise Inorganic Chemistry, Appendix E: Electronic Structures of the Elements [1, p. 601] provides two electronic configurations for berkelium: $$ \ce{Bk}\quad \begin{cases} [\ce{Rn}]~\...
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2 answers
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The existence of sodium carbide

(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 ...
6 votes
1 answer
522 views

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 ...
-2 votes
2 answers
738 views

Why silicon doesn't have the electronic configuration [Ne] 3s¹ 3p³?

I have read that half or fully filled orbitals provide more stability to the element due to symmetry and exchange energy.It is the reason for electronic configuration of Cr-[Ar]4s¹3d⁵. Then, why doesn'...
12 votes
3 answers
7k views

Why do iron(II) ions and chromium have different electronic configurations?

What I know: Empty 3d orbitals are higher in energy than empty 4s orbitals Aufbau Principle (electrons always go into an empty orbital with the lowest energy) Partially/half/fully filled 3d ...
2 votes
0 answers
370 views

Valence shell expansion and sulfur

I've been searching some things regarding the ability of sulfur to accomodate negative charge and reached the conclusion that it's due to its size and its ability to expand its valence shell. I can't ...
5 votes
2 answers
9k views

What does the subscript of atomic orbital mean?

As everyone knows, the atomic orbital can be classified as $s, p_z, p_x, p_y, d_{z^2},d_{xz},d_{yz},d_{xy},d_{x^2-y^2}$ and so on. I want to know the meaning of $z^2,x^2-y^2$ and so on. Maybe this is ...
4 votes
1 answer
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Cerium electronic configuration change from 0 to +2 oxidation state

Cerium in $0$ oxidation state has electronic configuration $$[\ce{Xe}]\mathrm{(4f)^1(5d)^1(6s)^2}$$ But when it gets oxidised to $+2$ state, it becomes $$[\ce{Xe}]\mathrm{(4f)^2(5d)^0(6s)^0}$$ ...

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