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.

36 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
7
votes
0answers
755 views

Chemical bonding with f orbitals

For the elements such as rhenium, osmium, iridium how probable is for electrons in the inner 4f orbitals to gain energy and take part in a molecular orbital (such as an $f^2 d^2 s p^3$ hybrid orbital) ...
4
votes
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 ...
3
votes
0answers
61 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 ...
3
votes
0answers
63 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 ...
3
votes
0answers
2k views

How do I explain these bond angles in SF4 and SOF4?

From here and here I found that the bond angle between the equatorial $\ce{F}$'s in $\ce{SF4}$ is less than that in $\ce{SOF4}$. I understand that is because of greater repulsion by lone pair than by ...
2
votes
0answers
84 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
votes
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 ...
2
votes
0answers
31 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 ...
2
votes
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 $...
2
votes
0answers
3k views

Why is the nitrile nitrogen sp hybridized?

This site, from which the above image was taken, indicates that the hybridization of the orbitals on the C and N atoms in hydrogen cyanide is sp. I can certainly see how that would be the case for ...
2
votes
0answers
2k views

length of bond, bond angle and p character in bond

My reference data: http://www.rsc.org/suppdata/ra/c4/c4ra06781a/c4ra06781a1.pdf Consider these five chemicals: A: $\ce{CH4}$ (methane) B: $\ce{CH3Cl}$ (chloromethane) C: $\ce{CH2Cl2}$ (...
1
vote
0answers
34 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
vote
0answers
263 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 ...
1
vote
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 ...
1
vote
0answers
121 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 ...
1
vote
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 ...
1
vote
0answers
278 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 ...
1
vote
0answers
153 views

Why is it not possible for seven close copper atoms to come together to gain a noble-gas configuration of valence electrons?

My textbook says the following about metallic bonding: The metal copper has one valence electron. The valence electrons of nearby copper atoms are shared in a similar way to covalently bonded ...
1
vote
0answers
522 views

Dichlorine monoxide molecular geometry

I need to predict the geometry of Dichlorine monoxide, using the main link theory: Lewis model, VSEPR and hybridization of molecular orbitals. First, the Lewis structure is a graphical representation ...
1
vote
0answers
871 views

How to calculate steric number of methyl free radical?

According to the definition, steric number = number of atoms it is attached + lone pair. In that way, I get 4 for methyl free radical which means sp3 hybridization . But that's wrong ! Why is this ...
1
vote
0answers
200 views

The affect of effective nuclear charge on energy gap between subshells

A few days ago my teacher taught me about $\mathrm{d}$ orbital contraction. He said that in $\ce{SF6}$ the hybridization of sulphur is $\mathrm{sp^3d^2}$. He said that although the $\mathrm{d}$ ...
1
vote
0answers
385 views

Hybridisation and bond strength

I'm a high school student with minimal mathematical knowledge about the theory of chemical bond. (I just have a bit of theoretical background). I came across a statement which stated that "The more is ...
1
vote
0answers
207 views

How do we explain shapes of molecules using molecular orbital theory or do we even do that?

How do we explain shapes of molecules using molecular orbital theory or do we even do that ? While reading about the theories to explain chemical combination and stabilities of compounds I read ...
1
vote
0answers
819 views

Why Don't Sulfur Atoms Hybridize?

I am doing some chemistry problems with given answers, and supposedly the $107^{\circ}$ and $92^{\circ}$ bond angles in $\ce{H_2O}$ and $\ce{H_2S}$, respectively, is due to the fact that"$\ce{O}$ uses ...
1
vote
0answers
49 views

Why does C=C bond replace C-O bond when two graphite platelets are rubbed against each other edge on edge?

When two small 2D carbon platelets are pushed into proximity, why do they release the edge attached molecule (maybe O) and then bond C to C? I think the answer I seek would address the relative ...
1
vote
1answer
1k views

Physical Meaning of the Difference between MO and VB Wave Function of H2?

What would be the physical meaning of the difference between the MO wave function and VB wave function of $\ce{H2}$?
1
vote
1answer
99 views

My text seems to say that the high(est) energy orbitals are not valence orbitals - everything else says otherwise. What's true?

A paragraph in my text reads Bonding involves the valence orbitals almost exclusively because these orbitals have the appropriate energies to interact strongly. Examine the electron energy-level ...
0
votes
0answers
346 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 ...
0
votes
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
votes
0answers
198 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 ...
0
votes
0answers
131 views

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 ...
0
votes
0answers
262 views

Why don't I get the same value of percentage ionic character of a particular molecule from different equations?

About the ionic character of a polar covalent compound Pauling gave two equations as [1-$e^{.25(x_a - x_b)}] $% [18$(x_a-x_b)^{1.4}$]% Hanary and Smith gave the equation [$16(x_a-x_b)+3.5(x_a-...
0
votes
0answers
788 views

Why are hybrid orbitals more efficient at overlapping?

What is the reason for considering that hybrid orbitals provide more effective overlapping resulting in formation of stronger bonds? Will this reasoning be correct that the hybrid orbitals have ...
0
votes
0answers
439 views

Comparing bond lengths of a molecule using valence bond theory?

My textbook says that all the bonds of $\ce{SF4} $ are not equal while in the case of $\ce{XeF_2}$, $ \ce{BF4-} $ or $\ce{SiF4} $ all the bonds are equal. No reason is stated for this observation. ...
-1
votes
0answers
71 views

Would uranium(XII) oxide be electron-deficient?

Uranium is six electrons ahead of radon and radon is six electrons ahead of mercury, so the uranium(XIII) cation, which is theoretically possible(see e.g. https://www.sciencedirect.com/science/...
-5
votes
0answers
24 views

Maximum covalency of sulphur

Why does sulphur stop at 6 bonds? Why can't it form 9 bonds because even after forming 6 bonds,it has empty d orbitals? And even if we consider steric factors, then why in the structure of sulphate ...