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Questions tagged [orbitals]

An orbital is a one-electron wavefunction, usually derived by solving the Schrodinger equation. This tag applies to questions about all forms of orbitals; additionally, questions about the construction and properties of molecular orbitals should be tagged with [molecular-orbital-theory].

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Why is the dz2 orbital so different from the rest?

What makes dz2 orbital so special? Although degenerate with other d orbitals, It has no nodal planes, instead it has 2 nodal "cones". Instead of having 4 lobes, it has 2 lobes and 1 ring. Also, ...
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Difference in Periodic Tables in Block Formation (split in d-block) [duplicate]

I had a question. When I was learning Chemistry and blocks in the periodic table, my professors always broke the table down like the image below Recently, when I looked up the periodic table (in ...
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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 ...
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Can pi backdonation occur on non-metal centers?

The common example of backdonation is the interaction of a CO molecule with a metal center (d-orbitals) on a surface. Can a similar mechanism occur between CO and a non-metal center, like oxygen on a ...
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38 views

Orbital size of Carbon and Oxygen in Methanal

I was given an introductory question into Carbonyl chemistry today and I wanted to ask a question about Methanal. The following picture was shown below of Methanal: and I noted that the orbital ...
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68 views

Disproportionation of Au(II)

Cu(II) and Ag(II) complexes are known to exist while Au(II) is unstable and disproportionates to Au(I) and Au(III). My guess as to possible reasons to this effect is that Au(II) like Cu(II) and Ag(II)...
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Electronic configuration of the actinides

I was reading about actinides and I need some help in understanding this paragraph from Concise Inorganic Chemistry by JD Lee - The electronic structures of the actinides do not follow the simple ...
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1answer
51 views

Why is $1s-1s$ orbital overlapping stronger than $2p_x-2p_x$ orbital overlapping?

Assume the x-axis to be the internuclear axis. Hence, both $1s-1s$ and $2p_x-2p_x$ will form $\sigma$ bonds. Also consider the fact that $p$ orbitals have more directional characteristics. Given the ...
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Half/fully filled orbital stability

Beryllium the configuration is [He] 2s2 i.e fully filled but still quite reactive Also in neon [He]2p4 , neither half filled nor fully filled, still quite stable compound (As it forms compound with ...
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How to Choose Orbitals for Hybridization

Recently, I was reviewing my textbook regarding orbital hybridization, and one of the problems was to determine the hybridization of each of the atoms in $\text{CO}_2$. I understand why the ...
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1answer
36 views

Why does ionisation energy to remove electrons from the same subshell increases? [closed]

Electrons in the same subshell possesses the same energy. So why does ionisation energy to remove electrons from the same subshell increases? For example, $\mathrm{2s^2}$ has two electrons. Since ...
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Removal of electrons from orbitals doubt

I recently encountered a question asking whether [PtCl4]2- has square planar geometry. I know that Pt has an electronic configuration of [Xe] 5d9 6s1, in the given compound Pt2+ is there, so the E.C ...
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1answer
56 views

Why does sp hybridised orbital have more directional character than p orbital?

It states so in my textbook. But since s orbital is non directional, shouldn't sp hybridized orbital be less directional in character than p orbital?
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1answer
69 views

Subscript on Orbitals [closed]

What do the subscripts on the orbitals (such as px, py, pzetc) mean and how can one derive these or at least gain a fundamental understanding of each? Do they describe the geometry of the shape? And ...
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107 views

Why does beryllium lose two electrons when it’s orbitals are already full?

I have a rudimentary understanding of orbitals, as in what they are, the shapes (l, I think) and of the principles. So I was doing the electronic configuration for beryllium, it has 4 electrons. So ...
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How to evaluate the expectation value of the Hamiltonian for a three electron Slater determinant?

I'm having trouble with a few concepts dealing with slater determinants and many electron systems. In particular, when dealing with 3 electron systems, I know that $$ \psi_0 = \frac{1}{\sqrt{6}} \det ...
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2answers
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Strange “far out” orbitals in HF and DFT calculations. Why do they occur?

I calculated some orbitals and I get quite strange results with orbital geometries I wouldn't expect from MO theory. A more experienced colleague just said: "That's always the case with big basis sets,...
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1answer
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Chemical bonding based on hybridisation model

A snippet from a textbook: Therefore, the hybridization model predicts that an $\mathrm{sp}$-hybridized carbon atom is more electronegative than an $\mathrm{sp}^3$-hybridized carbon atom. Evidence ...
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Why ionisation enthalpy of early lanthanides are expected to be greater than early actinides?

In my book Chemistry Part I (NCERT XII), a statement on p. 232 goes like this: It is evident from the behaviour of the actinoids that the ionisation enthalpies of the early actinoids, though not ...
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1answer
33 views

Identifying orbital given electron probability density plot

Being a high-school student, I only have a qualitative understanding of the wave mechanical model of atom. Below are my inferences regarding the plot shown in the above picture: The concerned ...
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1answer
164 views

Why are pi antibonding orbitals lower in energy than sigma antibonding orbitals?

I know when a carbonyl group is attacked by a nucleophile, the electrons of the nucleophile enter the antibonding π orbital of the $\ce{C=O}$ bond, which breaks the π bond. My textbook says that ...
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2answers
80 views

What about the aromaticity of cyclopropenylidene?

Here's a compound which we have to tell whether it's aromatic or not. Drawing pi-orbital for the 3-membered ring, I think there are only 2 pi electrons delocalised all over the ring. The orbital ...
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36 views

What is the difference between Orbitals and energy level? [duplicate]

What is the difference between Orbitals and energy level? The energy level is the same as an electron shell, right? And as far as i know Orbitals are area with high probability of finding an electron. ...
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Oxidative Addition - Really concerted?

I guess you are all familiar with the oxidative addition or reductive elimination reaction in organometallic chemistry. If you read further into the topic you may find different pathways like via ...
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1answer
125 views

Explaining why s and p orbitals do not interact

While going through molecular orbital theory, my chemistry teacher mentioned that the reason why there is no significant interaction between $\ce {s}$ orbitals on one atom and $\ce {p_x}$ and $\ce {...
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How do we recognise a Hybridised Sp3 orbital? [closed]

As far as i know the sp3 orbital is a combination of orbitals. But how do we know if we have a hybridised orbital or not?
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1answer
58 views

Aufbau principle in filling Ti

A few weeks ago, I was given this question to complete: The ground state electronic configurations of Ti is $\ce{[Ar] 4s^2 3d^2}$ State whether it follows the Aufbau principle or not. If not, ...
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1answer
251 views

What is the exact definition of the radial distribution function?

I have been very confused by the radial distribution function which is often used in chemistry to predict the probability of finding an electron at a distance from the nucleus. From Atkins' Physical ...
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1answer
41 views

what orbitals shape when we draw they together?(how do you shape orbitals together?) [closed]

If we want to draw all the orbitals of an atom, for example the atom of krypton, how will the space form of orbitals be when they are drawn together? in all scientific books,s,p,d and f orbitals shape ...
4
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1answer
160 views

How can f-f transitions happen?

The question might seem quite easy to answer but still I am unable to find any useful information. I am aware of laporte- or symmetry-forbidden transitions and for f-f also spin-forbidden transitions ...
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What is the magnetic moment of potassium hexacyanochromate(II)?

I calculated the magnetic moment of $\ce{K4[Cr(CN)6]}$? in the following way: $\ce{Cr^{+2}}$ has $4$ d electrons. And since $\ce{CN-}$ is a strong field ligand, the electrons will pair up in the $\...
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1answer
26 views

Angular Momentum Quantum Number and Orbitals

In our lecture I was told the angular momentum QN is equal to $n - 1$ of the principle QN, which corresponded to the orbital shape. How is this case, for example in Barium the principle QN is 6 with,...
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Why are the radial wavefunction and radial distribution function different?

I'm having trouble understanding the following two graphs, which are the radial wavefunction of the hydrogen 1s orbital and the corresponding radial distribution function: Specifically, why is the ...
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Implementing the projected atomic orbital (PAO) localization in Gaussian

I am currently attempting to learn how to setup the active space for performing CASSCF calculations. The textbook I am using as a reference is: Roos, Björn O. "Multiconfigurational quantum ...
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HOMO / LUMO energies in a qualitative view

I have a question regarding the HOMO and LUMO energies depending on various effects like substituents and electronegativity. It seems to be a somewhat known topic but I cannot really find a clear ...
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2answers
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Is the notion of orbitals different in theoretical chemistry?

I am just an average chemistry student that is currently exposed to theoretical chemistry. And I am seeing very puzzling things, such as 1p, 2f, 3g orbitals. In my attempt to reconcile this, I was ...
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Are any other orthonormalizations schemes besides Lowdin normally used when solving SCF equations?

When solving equations of the form: $$F(C)C = SC\epsilon$$ (e.g. Hartree-Fock-Roothan or Kohn-Sham-Roothan) where $F$ is the fock matrix, $C$ is the coefficient matrix and $S$ the overlap matrix, ...
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1answer
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How do I have to interpret the input to the OCC flag in Molpro?

I'm trying to understand the occupied orbital specification in Molpro. They're specified by the OCC flag, while it's stated in the documentation, that OCC, m1, m2, ..., mn; where the ...
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1answer
586 views

According to MO theory, why is the dilithium cation more stable than the dilithium anion?

According to molecular orbital theory, $\ce{Li2}$ fills up two electrons in the $\sigma_\mathrm{g2s}$ molecular orbital; $\ce{Li2+}$ fills up one electron in the $\sigma_\mathrm{g2s}$ MO, and $\ce{...
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1answer
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Molpro - Simple explanation of OCC, CORE, FROZEN and CLOSED orbitals

I'm beginning with quantum chemistry and I'm supposed to do some ab initio calculations with Molpro. The problem is, I don't understand the orbital specification very well. Let's say, I have the ...
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Reducible representations - choice of new basis

I was looking at this tutorial about reductions of representations. At first, the basis consists of four orbitals $(s_N, s_1, s_2, s_3)$ and the representations look like this and we want to reduce ...
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What is the difference between carbon in an excited state and with sp³ hybridization?

What is the difference between the carbon in the excited state, $\ce{[(1s)^2] (2s)^1 (2p)^3}$, and $\pu{sp^3}$ hybridization?
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If a single electron fills a degenerate energy level, does it fill all degenerate orbitals at once?

For example, if a single electron fills the 2p orbitals. Since all orbitals are degenerate, there is no reason why there would be any preference for px, py, pz. Is the electron hence in a ...
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2answers
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The molecular orbitals of lithium hydride

So my understanding of molecular orbitals is as follows: the molecular orbitals of $\ce{LiH}$ can be thought of as being formed from the interaction/overlap of two atomic orbitals, one from lithium ...
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1answer
47 views

What are the magnetic quantum numbers for specific d orbitals? [closed]

I mean I know they’re $\ce{d_{-2}}$, $\ce{d_{-1}}$, $\ce{d_{0}}$, $\ce{d_{1}}$, $\ce{d_{2}}$ but how do these numbers relate to each one of $\ce{d}$ orbitals $\ce{d_{z_2}}$, $\ce{d_{xz}}$, $\ce{d_{yz}}...
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Why do the 4f and 5d orbitals have similar energies?

I've come to know this phenomena when learning about the exceptions to the aufbau principle. But there is no explanation of why 4f and 5d have similar energies (as I've read in some websites).
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1answer
275 views

Are the 2s and 2p subshells degenerate in the He+ ion?

I know that the 2s and 2p (as well as 3s, 3p, and 3d) electron subshells are degenerate in the hydrogen atom. I was wondering if they are also degenerate in other one-electron species, such as the $\...
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How is the structure of triiodide ion (I3-) possible?

I have seen the structure of triiodide ion ($\ce{I3-}$) but I cannot understand why this structure is even possible. I have seen in my textbook that $\ce{I_3^-}$ is formed by combination of $\ce{...
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Why are 4s electrons removed before 3d electrons? [duplicate]

According to Aufbau's Principle energy of 3d orbital is greater than 4s orbital, so which filling 4s if filled beforehand 3d. Whereas while removing electrons 4s electrons are removed first. Why? I ...
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1answer
1k views

Rule to determine the total number of elements in a period [closed]

If each orbital can take maximum of 3 electrons, then total number of elements in 2nd and 4th periods respectively are = ? I am not aware of the rule which helps to determine the total number of ...