Questions tagged [valence-bond-theory]

Questions about how the atomic orbitals of the dissociated atoms combine to give individual chemical bonds when a molecule is formed.

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8
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1answer
173 views

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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0answers
56 views

Why is the bond angle of sulphur difluoride greater than that of hydrogen sulphide?

Why is the bond angle of $\ce{SF_2 (98.05^\circ) > SH_2 (92.11^\circ)}$? Isn't this contradicting Bent's rule or otherwise electron repulsion rule ? Fluorine is more electronegative and hence it ...
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0answers
56 views

How are 3 center-4 electron bonds any different from 2 center-2 electron bonds? [closed]

How are the bridge bonds in $\ce{Al2Cl6}$ different from the terminal bonds? We could have just mentioned the bridge bond formed by $\ce{Cl}$ as a coordinate bond. Why introduce this extra concept? I ...
2
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82 views

Why does NH3 cause pairing in case of some metal complexes and doesn't in case of others?

I was met with a question that required me to find which complex is an outer orbital complex, and two of the options included $\ce{ [Ni(NH3)6]^2+}$ and $\ce{[Co(NH3)6]^3+}$, I want to know why does $\...
2
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0answers
67 views

Application of statement: extent of overlapping is always less than 50% because of electronic repulsion [closed]

Question from the online class: Can two s-orbitals overlap as shown? Dotted circles in diagram depict maximum probability region of s-orbitals in ideal situation when atoms A and B are not bonded. ...
2
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2answers
275 views

Explain on the basis of valence bond theory that tetracyanonickelate(II) ion with square planar structure is diamagnetic

Answers on the internet suggest that tetracyanonickelate ($\ce{([Ni(CN)4]^{2-}}$) with square planar structure is diamagnetic because $\ce{CN-}$ is a strong field ligand and causes pairing, but my ...
-2
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1answer
61 views

Hybrid lobes of sp3d2 and sp3d3 [closed]

It's known that $\ce{sp^3d}$ hybridization has 5 lobes; 3 equatorial with $\ce{sp^2}$ lobes and 2 axial with $\ce{dp}$ lobes. Do we have such splitting in $\ce{sp^3d^2}$ and $\ce{sp^3d^3}$ ...
-1
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1answer
68 views

Why is it that nitrogen hybridizes in ammonia, yet in F2, fluorine does not [closed]

It seems rather arbitrary to me that we have decided that nitrogen sp3 hybridizes in ammonia to stay consistent with VSEPR, yet that fluorine uses its 2p orbital to bond with another fluorine in F2 (I....
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2answers
45 views

do electrons in different orbitasl in a same subshell have same energy

In valence bond theory, I suppose that electrons in say, 2px and 2py have the same energy because of the same structure of orbitals. But what about 3dxy and 3dz^2? Do they also have the same energy? I ...
1
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1answer
62 views

What is the difference between resonance and π conjugation

I have seen electron delocalization mentioned frequently in 2 separate contexts: resonance (ozone, carbonate / nitrate...) and π-conjugation systems (aromatic compounds). While the 2 initially sound ...
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0answers
29 views

is there a stead fast rule to predict hybridization or is it just an ad hoc concept

Before I start of this question, Ι want to make it clear that I know that hybridization, like pretty much all of chemical bonding, are just made up to qualitatively rationalize observations. I know ...
3
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2answers
120 views

Why does delocalization (only) occur in molecules represented by resonance hybrids?

Before I start this question, I am aware tha Electrons in all molecules are delocalized to some extent Delocalization is a the phenomenon and resonance is an attempt to explain it. When I asked this ...
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29 views

what does “overlapping” of orbitals mean and why does it effect bond strength(VBT)?

according to valence bond theory, bonds are formed due to the pairing of unpaired valence electrons due to the overlap of half-filled orbitals, and the strength of the bond depends on the extent of ...
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33 views

Direction of valence bond and Unsöld's theorem

Is it true that the atomic orbitals of separate atoms already have directionality, which ensures the directionality of the valence bond? Or another words, what is the real spatial distribution of the ...
-1
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2answers
202 views

Why there is no sp2s hybridization in hydrocarbons? [closed]

If carbon's $\mathrm{sp^2}$ orbital is overlapped with hydrogen's $\mathrm{s},$ then why it is $\mathrm{sp^2}$ and why not $\mathrm{sp^2s}?$
3
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1answer
146 views

Which combinations of orbitals lead to pi bonds according to Valence Bond Theory?

How many of the following combination of the orbitals will lead to formation of $\pi$-bonds with $z$ axis being the internuclear axis: $$p_x+p_x,\,p_z+p_z,\,p_y+p_y,\,d_{zx}+p_x,\,d_{zy}+p_y,\,s+p_y,\,...
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2answers
61 views

Transition metals with closed shells

From wiki page about valence electrons: An atom with a closed shell of valence electrons (corresponding to an electron configuration $s^2p^6$ for main group elements or $d^{10}s^2p^6$ for transition ...
2
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2answers
105 views

Insight into covalent bonds from electrostatic perspective

I try to understand, from the electromagnetic side only, how the molecule could be more stable than each atom, and concluded that it could not. Where is my mistake? Here is an illustration : By using ...
4
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0answers
113 views

Misconception in valence bond theory

Since the overlap increases with directional properties of orbital, $$\ce{p - p > s - s > s - p}$$ However it is also observed that the bond strength of $$\ce{H-F > H-H > F-F}$$ $$\ce{\{s ...
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0answers
260 views

Comparison between Molecular Orbital Theory and Valence Bond Theory

I have been reading about introductory Molecular Orbital Theory lately. Till now, I have used Valence Bond Theory to evaluate bonding. I have a few questions about it:- In VBT, we used the idea that ...
0
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1answer
52 views

Why isn't just a fully occupied valence s orbital stable?

Why arent elements like calcium with an electron configuration of $[\text{noble gas}]\ n\mathrm{s}^2$ stable, although all the populated orbitals are fuully filled? Why is it necessary to obtain an ...
0
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1answer
1k views

Maximum number of coplanar atoms in difluorotrimethylphosphorane

In $\ce{PF2(CH3)3},$ what is the maximum number of atoms lying in one plane? $\ce{P}$ is the central atom with the hybridization $\mathrm{sp^3d}.$ Two $\ce{F}$ atoms will form axial bonds with it, ...
3
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1answer
80 views

But what are anti-bonding pi-orbital? In search for an intuitive explanation [closed]

Imagine that you want to explain to an undergraduate why they have to to shade the pi-orbitals in a symmetrical way, i.e. dark on top (+), white on bottom (-) for two neighbouring pi-orbitals because ...
-1
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1answer
92 views

Is hypervalency a real thing? [duplicate]

I saw a proper debate going on between answers to a question about whether the octet rule could be violated. Some people were pointing to hypervalency in period 3 elements, due to the available d-...
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1answer
138 views

How to determine the shape of hybridized atomic orbitals in VB theory?

From diagrams, it's rather obvious how $sp$ orbitals are hybridized - the hybrids are just a composite of the $s$ and the $\pm p_{(x)}$ orbitals. However, $sp^2$ orbitals are not just composites of $s,...
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0answers
262 views

Hybridization state of oxygen in carbonyl sulfide (COS) [duplicate]

I've been scratching my head on this one for awhile here. In a carbonyl sulfide (COS) molecule, what is the hybridization state of oxygen? Carbonyl sulfide is composed of a single carbon atom double ...
0
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1answer
136 views

Backbonding in phosphorous pentoxide

I read this today in a book that $\ce{P=O}$ in $\ce{P4O10}$ consists of a coordinate bond and pπ-dπ backbonding, but why does this happen? Can't phosphorus share its lone pair with one of the lone ...
0
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1answer
167 views

Why does this ligand form 6-coordinate complexes with Transition elements and 8-coordinate complexes with Inner transition elements? [closed]

What change takes place in the denticity of this ligand if it is an inner-transition metal ion vs a common transition metal? Primarily, why does the ligand behaves differently with the two situations ...
3
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2answers
513 views

Comparing bond angles in carbonyl dichloride and carbonyl dibromide

Background I was studying VSEPR and hybridization theory and one of the popular questions in many textbooks was comparison of bond angle of $\ce{NH3}$, $\ce{NF3}$ and $\ce{NCl3}$. $\ce{NF3}$ had ...
7
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2answers
180 views

Hypervalency of orthonitrate

I have always believed that it is impossible for the atoms of period 2 elements (when they are the central atoms in polyatomic ions/molecules) to accommodate more than 8 electrons in their valence ...
3
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3answers
124 views

Effect of magnetization on oxidation (rusting) of iron

Can magenetizing a piece of iron bar slow-down (or speed-up) the oxidation (rusting) process? In other words have any influence on it ? From what I've looked up( wikipedia, quora), it appears that the ...
2
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0answers
47 views

Can one describe the bonding of Na to F in terms of molecular orbital theory? What about valence bond theory?

I would kindly appreciate an explanation in terms of the two accepted quantum mechanical theories -valence bond & molecular orbitals- for the electronic energy level structure in natrium fluoride $...
3
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1answer
691 views

Bonding and coordination of oxygen in a Ga2O3 crystal structure [duplicate]

I'm trying to find the crystal structure of gallium oxide ($\ce{Ga2O3}$). However, I find the images of the crystal structure in the peer-reviewed journals problematic. First, I hop to the wikipedia ...
3
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0answers
61 views

(Mis)understanding on MOT

In VBT, one can understand the example of hydrogen like this - Two hydrogen atoms come closer to each other, and their orbitals overlap, stabilize, and ultimately result in a bond. This is not too ...
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0answers
39 views

Hybridization theory (orbitals used in different hybridizations)

Why is $d_{x²-y²}$ orbital used in $sp^3d$ (square pyramidal geometry) while $d_{z^2}$ orbital in $sp^3d$ (trigonal bipyramidal geometry)? I came across this information while reading J.D.Lee Concise ...
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0answers
31 views

Reconciling electron configuration and valence electron distribution over separate energy levels in energy band theory [duplicate]

The electron configuration of a Silicon atom in its ground state is $\ce{1s^2 2s^2 2p^2 3s^2 3p^2}$, or equivalently, $\ce{[Ne] 3s^2 3p^2}$. When looking at the energy-level scheme of a silicon atom, ...
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0answers
117 views

Valency of each atom in a molecule with python

Consider ethanol, where each carbon atom has a valency of 4 and oxygen a valency of -2. I would like to determine these values for many compounds given their SMILES or InChI keys. (For the purpose of ...
0
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1answer
117 views

Confusion about hybridization terminology

I was just introduced to the concept of orbital hybridization. I believe I understand the idea behind it, but there is some accompanying terminology that prevents me from achieving a greater ...
1
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1answer
940 views

Magnetic nature of tetraamminedichlorocobalt(III) chloride

I know how to predict magnetic nature when the compound contains only strong field or only weak field ligands. But in $\ce{[Co(NH3)4Cl2]Cl},$ $\ce{NH3}$ is a strong ligand whereas $\ce{Cl-}$ is a weak ...
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0answers
50 views

Is bonds in CO is all 3 coordinate bonds or 2 covalent and 1 coordinate bonds?

Below image is as available in India's Class 11 NCERT Chemistry book vol 1 Page 104. I am confused as it states all 3 bonds are kind of coordinate bonds. Should it not start with 2 covalent bonds and ...
0
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1answer
379 views

Why is the valency of the Calcium (Ca) Bohr model, set to 2 electrons, instead of 1 electron for stability? [duplicate]

This is an Ascii table for the elements on the 4th period (row) of the periodic table, and distribution of electrons in each orbit. ...
0
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1answer
3k views

What is the hybridization of chromium in chromate and dichromate ions?

I was recently reading about the transition metals and some important compounds of them. I came across a rather interesting diagram in my book... a tetrahedral structure for the chromate ion. The only ...
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0answers
260 views

Why are sulfur trioxide and nitrate not isoelectronic, even though both have the same number of outer electrons?

Though $\ce{SO3}$ has the same number of outer electrons as $\ce{NO3-}$, the two are not isoelectronic. This statement is from JD Lee, but I could not understand why is he calling these two molecules ...
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0answers
332 views

Why do the d orbitals contract when pairing of electrons start, because the size should increase due to increase in energy

The energy of an orbital is proportional to its mean radial distance, and since the 3d orbital is much larger it is much higher in energy than the 3s and 3p orbitals All references from JD Lee ...
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2answers
546 views

Bonding in the nitrate anion [duplicate]

Hi so I was studying chemical bonding where i encountered a problem which is stated below. When we talk about ${NO_3}^-$ we draw its structure as following But the thing which I dont understand is ...
0
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1answer
2k views

Bond dissociation energy among halogens [duplicate]

Among the halogens, why is it that the fluorine has the lowest bond dissociation enthalpy, considering the fact that fluorine is the smallest and the internuclear distance between the fluorine ...
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0answers
32 views

How one can calculate Si-O-Ca/Mg valence angle energy?

I want to perform the relaxed scan (or relaxed surface scan) for the valence angle energy of Si–O–Ca, Si–O–Mg, Al–O–Ca, and Al–O–Mg. I will use DFT (ORCA), probably B3LYP and triple zeta basis set (...
0
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0answers
45 views

Reason behind hybridisation [duplicate]

I have been taught that orbitals can overlap only when all of them are in the same energy state. That is the reason why the orbitals hybridise in a kind of 'mixing up' and give rise to orbitals having ...
4
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2answers
144 views

Is dihydrogen the only example of overlap between two s orbitals?

I heard that $\ce{H2}$ is the only example of s–s orbital overlap. Can anyone give an example which contradicts this statement?
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189 views

Why are d(xy),d(yz) and d(xz) orbitals involved in d³s hybridisation?

Shouldn't d(x²-y²) dxy and dz² orbitals participate? Since this corressponds to the best case overlap? What factors decide the participating orbitals in hybridisation? P.S I am well versed with the ...