Questions tagged [molecular-structure]

This tag should be applied to questions that deal with the particular arrangement of atoms in a molecule, the so-called molecular structure or geometry.

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2answers
342 views

What elastic polymeric material look like at molecular level?

I think there are few crosslinks in elastic material. So probably, the material would look like not so dense, maybe even transparent. I received this question from my collegue and have difficulty in ...
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1answer
80 views

Variation of angle in GeX2 molecules where X is an halogen

I'm wondering what is the exact reasoning to explain why in $\ce{GeX_2}$ the angle $\widehat{XGeX}$ is smaller when $\ce{X}=\ce{F}$ than when $\ce{X}=\ce{I}$. I ask this question because I had an ...
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1answer
3k views

Why does the PH3 geometry deviate more from the trigonal planar one, than does NH3?

$\ce{PH3}$ has a more bent structure than $\ce{NH3}$. The HOMO-LUMO gap for $\ce{PH3}$ is smaller than for $\ce{NH3}$, and so the distortion from the trigonal planar geometry is said to be larger. ...
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1answer
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why do electron pairs not take axial positions in the VSEPR structure of ClF3? [duplicate]

when we make a Valence shell electron pair repulsion theory based structure for an molecule after calculating its hybridisation ; when we have to decide the positions of the ions we put them in such ...
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1answer
8k views

Structure of OSF4

Recently I had given a test where I was asked to specify the hybridisation of $\ce{OSF4}$ and its structure. I guessed that the structure would be trigonal bipyramidal, but I was unsure since I hadn't ...
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1answer
915 views

skeletal structure of dimethylamine? HN(CH3)2 [closed]

I don't understand how to draw this skeleton. I know there is a NH2 in an amine structure, but this only has NH? and dimethyl means there a 2 identical single side chains right? but where on the ...
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1answer
2k views

How is a side-group that contains a double bond named?

In my chemistry lecture, we are working on the naming and nomenclature of organic molecules. When we got to the naming of alkenes and alkynes, we were told that the functional group had to be in the ...
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1answer
2k views

What is the geometrical structure of Pb3O4?

I'm confused by the structure of Pb3O4. There are some sites claiming that it is a six membered ring of alternating Lead and Oxygen atoms with another Oxygen atom in the center bonding with 2 out of ...
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1answer
492 views

How can I find the bond angles for carbamic acid?

I need to find the bond angles for carbamic acid (as a self-given practice). As I understand it, the structure looks like this: ...
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2answers
2k views

Estimation of the bond angle of water

We know from experimental data that $\ce{H-O-H}$ bond angle in water is approximately 104.5 degrees. If its two lone pairs were bonds (which is unfortunately impossible) also $\ce{O-H}$ bonds and a ...
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Which bond angle will be larger in a compound like CH2X2?

Just thought of a certain situation.Say for example in a compound like difluoromethane $\ce{CH2F2}$ or $\ce{CH2Cl2}$ obviously the tetrahedral structure will be distorted. But my question is which ...
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Can one component of a mixture penetrate the skin if the whole mixture cannot?

There's a general rule that says that compounds under 500 dalton are able to penetrate the skin without any special vehicle (such as ethanol). I've started using castor oil, which contains different ...
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2answers
808 views

Pyramid Structure Name

I would like to know what the name is for the structure drawn below. This looks like a pyramid with 4 atoms at each vertex. Does the name of the structure depend on whether the atoms are all the same ...
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Interpreting the MOs of a molecule [closed]

I've been looking at the MO:s of different molecules in Avogadro, fascinated by their magnificent geometries. But how is one supposed to interpret them, so as to understand their reactivity? What are ...
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1answer
796 views

Why are glycosidic bonds always 1->4 in polysaccharides?

I know 1->6 bond exists too, in amylose for example, but that one seems logical, since the 6th carbon is easier to access. I understand why the bonds originate from the hemi-acetal carbon, but I don'...
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2answers
568 views

Hemp and Cotton

Hemp fibre has a higher tensile strength and toughness than cotton. Could anyone explain how their different chemical compositions and molecular structure (E.g. beta sheets if any present, bonding,etc....
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3answers
829 views

How many coordinates should be used for the potential energy surface of a non-rotating linear molecule? (3N-6) or (3N-5)?

Take, for example, $\ce{CO2}$. It is pretty clear that in the absence of rotation, the energy of this system depends only on the two bond lengths and the bond angle. So if I wanted to build a ...
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0answers
583 views

Difference of aggregate and cluster?

Can anyone tell me the difference of aggregates and clusters from the molecular point of view? Thank you so much.
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1answer
1k views

How to draw glucose using a Fischer projection?

I asked how to draw glucose as a Fischer projection from its given chair conformation but all I got was an unsatisfactory ad hoc explanation involving rotation of my neck muscles to somehow see where ...
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53 views

Is there any porous material that can have narrow parallel and "perfectly straight" cavities/holes through it (or bored through it)?

I'm basically looking for a material that can allow photons to pass through its cavities, but only those photons that travel at an angle (almost) exactly perpendicular to the materials surface. Non-...
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1answer
567 views

Structure diagrams indicate plausible structures? [closed]

Structure diagrams have a hexagonal, "chicken wire" shape, which leads to more elegant representations of some molecules than others. For example, the following diagram must deviate from the usual ...
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1answer
9k views

What is the difference between saturated and unsaturated fatty acids?

Chemically speaking, what are the biggest differences between saturated fatty acids and unsaturated fatty acids? What are the effects of those differences on the geometry of the molecule? And what is ...
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0answers
95 views

Invariants in chemistry used for model selection

What invariants related to geometrical structures that describe molecular geometry are used in chemistry? Explanation: Here, Electronic model with highest prediction rate…, one can learn about ...
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0answers
194 views

What is the justification for Ligand Close Packing Model?

The LCP model predicts that nonbonded atom to atom distances remain approximately the same when the central atoms are changed. What is the theoretical justification for this? thanks
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1answer
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How can rotamers of alpha-keto esters be named to distinguish between different geometries?

When talking about free rotation it is often helpful to determine about which geometric arrangement one is referring to. For example in the case of butane we talk about several eclipsed or staggered ...
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2answers
801 views

Which element should be placed in axial position bulky one or the smaller one?

In one question for finding $\ce{P(CH3)2H3}$ structure? Which one should be placed in axial position? I think $\ce{-CH3}$ should be axial position to minimise repulsion.
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O-N-O bond angles in oxides of nitrogen

If we look at the bond angles of O-N-O in figure (c), (D) and (F), there not too much change in bond angle. Even though they are notable. So my question is, Why do we observe very small change in ...
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1answer
337 views

Geometries of methyl and silyl radicals

The $\ce{.CH3}$ radical is planar but the $\ce{.SiH3}$ radical is a trigonal pyramid. Why are they different? After all, $\ce{C}$ and $\ce{Si}$ are in the same group.
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1answer
856 views

What are the structures of potassium superoxide and xenon hexafluoride? [closed]

I have 2 questions in mind: 1) What is the structure of the superoxides? More specifically, what is the structure of $\ce{KO_2}$? 2) What is the structure of and dipole moment for $\ce{XeF_6}$?
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2answers
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What's the difference between a tetrahedron and a trigonal pyramid?

The shapes respectively denoted by 'tetrahedron' and 'trigonal pyramid' seem to be the same. Is there a difference between the two? If not, why are the two presented as different concepts in ...
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0answers
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Why are H2O asymmetric while CO2 is not? [duplicate]

What is the reason for water molecules $\ce{H_2O}$ being asymmetric while other molecules like $\ce{CO_2}$ being completely symmetric? See the pictures below: In both case there is an electronegative ...
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1answer
654 views

How does the pyramidalization effect the bonding angles in a distorted octahedral environment?

This is a follow up on "Generally Octahedral - Meaning?". Since Dissenter asked in the comments to my answer: I'm not sure why the $\ce{F_{eq}-S-F'_{eq}}$ bond angles would be compressed, even if ...
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1answer
167 views

Structure of Niobium and Tantalum carbonyls

$\ce{V(CO)6}$ is well known to be an unusual 17 valence electron, paramagnetic octahedral complex. Do the corresponding tantalum and niobium species form simple dimers or more complicated structures ...
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1answer
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Full Valence Shell (Octet Rule) vs Formal Charge

When does formal charge have more precedence over the octet rule / an atom having a full valence shell when drawing structures? When you draw $\ce{BCl3}$ for example, there are no double bonds - ...
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0answers
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Interstitial sites: edge and face sharing?

In close packed structures there is one octahedral hole per close packed atom. In a HCP unit cell these octahedra form a chain of face sharing polyhedra. Is this this universal in close packing or ...
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1answer
3k views

Dichromate ion: Tetrahedral or bent?

I am currently studying about the vespr theory and I'm stuck on an ion which is dichromate (VI) ion $\ce{Cr2O7^2-}$. So this is what I am thinking about: 1) If I make the oxygen atom at the middle ...
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1answer
68 views

Why do many hypervalant chemicals have non-constant bond angles?

According to the VSEPR model, when a molecule in formed in the shape of $\ce{AB_{x}}$, like $\ce{IF7}$, $\ce{SCl6}$, and $\ce{PCl5}$, its structure is found by reducing the repulsions between ...
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0answers
29 views

What is the mean curvature of nitrates and nitrites?

I am reading the book Soft Matter Physics - Synthetic and Biological Self-Assembling Materials from Hamley and particularly page 201. I started to think how this packing occurs in case of molecules ...
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1answer
4k views

Why does Fe(CO)₄ adopt a tetrahedral, as opposed to square planar, geometry?

Why does $\ce{Fe(CO)4}$ adopt a tetrahedral, as opposed to square planar, geometry? Here's my analysis: Factors for square planar: coordination: 4 $\ce{Fe(0)}$: d8 $\ce{CO}$: strong field ligand (...
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3answers
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What is the geometrical structure of OF₂?

Is it linear, angular, triangular or tetragonal? Well, since $\ce{O}$ has 2 electron matches of his own, I think it's tetragonal, but in wikipedia it is angular... Why? What about $\ce{CS2}$, is it ...
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1answer
919 views

Build the geometric structure of SnBr2

What is Sn valence in this case? Because it depends on it if it will be linear or tetragonal.I'm talking about a molecule.
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1answer
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Why is aluminium carbide bent?

The geometry of aluminium carbide is attached. Why isn't it completely linear (in accordance to VSEPR), but bent on the Al atoms?
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1answer
788 views

What is the geometric formula of CaI2 and AlCl3

Well, I think $\ce{CaI2}$ is the same as $\ce{BeH2}$ and $\ce{AlCl3}$ the same as $\ce{NH3}$, but I'm not sure since $\ce{I}$ and $\ce{Cl}$ have their own pair electrons and I don't know if this ...
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2answers
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What are the bond angles in cyclohexane?

In the chair conformation of cyclohexane, what are the angles of the triangles defined by: a carbon atom, an axial hydrogen bonded to it, and the midpoint of a vicinal C-C bond ? a carbon atom, an ...
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1answer
136 views

How do I convert zwitterions to neutral form in Avogadro?

I'd like to be able to convert zwitterions to neutral form in Avogadro if possible. How do I do this?
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1answer
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How is bismuth(III) able to form 3 bonds with hydroxide molecules in bismuth(III) hydroxide?

Bismuth(III), if I am not mistaken, has only two valence electrons in the 6s orbital. However it is able to form 3 bonds with hydroxide. This goes against my intuition. How is it able to form 3 bonds ...
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1answer
386 views

IBrF2 - van der Waals repulsions - and number of unique bond angles

I understand that the molecule $\ce{IBrF2}$ is T-shaped, with three ligand atoms and two non-bonding pairs. However, how many unique bond angles can this molecule exhibit? My professor argues for ...
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"Generally Octahedral" - Meaning?

What does this question mean by generally octahedral? Can this molecule adopt other shapes? Also I have my suspicions about the Br-S-F bond angle being a perfect 180 degrees. Wouldn't vdW repulsions ...

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