Questions tagged [crystal-structure]

In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid.

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11
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1answer
213 views

Software to assist drawing of complex, three-dimensional skeletal formula from scratch or from existing crystal structure

Is there a tool that would help in creating rather intricate line drawings (not pre-rendered balls-and-sticks/wireframe/sticks/ORTEP diagrams) for a skeletal formula in 3D space? To illustrate the ...
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Why upon melting of PEO between crossed polars colours appear?

Crystalline PEO when under crossed polars shows distinct Maltese cross pattern. Being birefringent, when polymer crystal align with the polarizer or analyser it shows extinction regions (effect known ...
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1answer
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What do X-ray diffraction and NMR tell about the Proteins? [closed]

I have gone through a simple idea that proteins have different conformations; it is a dynamic system. Moreover, whenever we do ensemble experiments, so we get an average picture. There are some ...
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1answer
40 views

What is a material more easily cut than shattered? [closed]

I'm currently developing a sci-fi concept for animation which partially involves a typical "the earth has been overrun by XYZ" scenario. One of the ideas for XYZ we're thinking of is a species of ...
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Crystal structures of heaviest nuclides' compounds

What is the heaviest element of the periodic table for which there is a compound whose crystal structure has been completely resolved by X-ray diffraction?
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If the appearance of a crystal is octahedral crystals, can I deduce that the crystal structure is octahedral?

I have a physics problem in which I'm calculating the magnetic properties of "a paramagnetic salt like iron ammonium alum". I am half inclined to believe that I am supposed to treat the substance ...
5
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1answer
221 views

Unexpected result (sodium hypochlorite & steel wool)

So I got myself a large Erlenmeyer flask, some steel wool and the bleach from the bathroom, mixing them under safe conditions in small quantities to see the sparky reaction I'd heard about. Trouble is,...
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32 views

How to control nucleation of NaCl crystals?

In addition to a previous question I posted, I have a second question. The previous question I shall link here: How to counter crust formation when crystallizing NaCl on the liquid-air interface? ...
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How to counter crust formation when crystallizing NaCl on the liquid-air interface?

Saturated sodium chloride solutions are evaporated at elevated temperature. The aim of evaporation is to produce hollow pyramid salt crystals. Temperatures used range from 65°C to 85°C. With 80°C ...
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Crystal structure of solid (frozen) hydrogen fluoride?

Wikipedia says the HF molecules form zig-zags, but doesn't mention any larger-scale organization. Is it amorphous, similar to glass? (https://en.wikipedia.org/wiki/Hydrogen_fluoride)
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Does bicarbonation require water?

In an aqueous solution of $\ce{NaOH}$ exposed to the atmosphere one can probably expect some degree of $$\ce{NaOH(aq) + CO2(g) -> NaHCO3 (aq)}$$ But, what would happen if just a solid block of $\...
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Symmetry Space Group Diagram

I am doing an introductory course to Crystallography and I have found in the following web page: http://pd.chem.ucl.ac.uk/pdnn/symm3/sgmonoc.htm a guide for the elaboration of the diagrams of the ...
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56 views

Ce₂(SO₄)₃ solubility in water [duplicate]

I have mostly come across examples of solids whose solubility increases in liquids with an increase in temperature. However, there seem to be exceptions to generalized rule this such as the solubility ...
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1answer
50 views

Are there examples of crystals with random but static mixtures of two unit cell configurations?

The image in this question turned out to probably be wrong, but it still makes me wonder. Are there examples of crystals where the atoms within a unit cell can have two (or more) different ...
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63 views

Crystallographic terminology associated with the honeycomb structure

I'm trying to quickly learn basic crystallographic principles in 2D under pressure (it's me whose under pressure, not the lattice) so I'm checking many sources to find those that "speak to me" the ...
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257 views

Calculating distance between adjacent planes (hkl) in a simple cubic crystal

My textbook says the following in a section on Miller indices: Adjacent planes $(hkl)$ in a simple cubic crystal are spaced a distance $d_{hkl}$ from each other, with $d_{hkl}$ given by: $$d_{...
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Question about Elemental Sulfur

I am trying to understand the structure of elemental, crystalline sulfur. I read that it is face-centered orthorhombic. My question is whether each point on the unit lattice contains a single atom of ...
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1answer
59 views

Miller indices: How does one translates the orientation to the origin of the unit cell?

In a section discussing Miller indices, my textbook says the following: The rules for determining the Miller indices of a direction or an orientation in a crystal are as follows: translate the ...
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2answers
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How can I find the smaller symmetric structure from big crystal unit cell?

I have Pyrope (Mg3Al2(SiO4)3) crystal structure, downloaded from materialsproject: https://materialsproject.org/materials/mp-6073/# It appeared as triclinic cell, but if you download CIF file and ...
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3answers
164 views

Why doesn't beryllium, an elemental solid, obey Dulong and Petit's law?

Beryllium has a molar heat capacity of $\pu{17.7 J mol-1 K-1},$ which is quite far from the $\pu{25 J mol-1 K-1}$ as predicted by Dulong and Petit's law. What is the reason for this discrepancy?
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100 views

Why is Polonium the only metal to crystallize forming Simple Cubic Cell?

I have read that Polonium is the only metal that crystallizes forming SCC. I searched for a concrete explanation but all they were saying is the stability of Polonium at STP. I can't really comprehend ...
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1answer
81 views

When H2NCH2CH2PH2 acts a monodentate ligand, it is the phosphine end that chelates. Why is that?

In some occasions, if the ligand acts on Pd it do so as a monodentate ligand. I am attempting to explain this phenomenon but came into a block.
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2answers
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Why is Libethenite (Cu2(OH)PO4) color green?

It is not a complex compound and the copper atom is not oxidized so I'm wondering how does its color change. The book mentioned that at favorable conditions, adding water in Copper phosphate, which is ...
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Understanding lattice matching of graphene on silver (111) crystal surface and meaning of the √3 x √3 lattice?

Figure 1 in Ivor Lončarić and Vito Despoja, Phys. Rev. B 90, 075414 Benchmarking van der Waals functionals with noncontact RPA calculations on graphene-Ag(111) (available in Researchgate) shows a ...
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267 views

Silver (111) surface structure, and is bulk structure body-center or face-center cubic?

I'd like to understand the atomic arrangement is on a silver (111) surface. Step 1 would be to find out the bulk crystal structure. Wikipedia lists silver as face-center cubic (fcc) here and here ...
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1answer
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Why don't ionic compounds show stereoisomerism?

When I was reading about crystalline nature of ionic compounds, I came across the statement that ionic compound doesn't show stereoisomerism. What does that mean and can anybody explain the reason ...
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1answer
61 views

Lattice energy while bond formation [closed]

My chemistry lecturer taught us that lattice energy is the energy required to break an ionic bond between two oppositely charged ions in a crystal lattice. He then told us that lattice energy is ...
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Could you form quartz crystals by melting and cooling sand very slowly?

Since glass is amorphous quartz and when you slow the cooling of something enough it will crystallize, couldn’t you melt $\ce{SiO2}$ (sand) and then very slowly cool it to cause spontaneous nucleation ...
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What would superionic water ice look like?

Phys.org's Giant lasers crystallize water with shockwaves, revealing the atomic structure of superionic ice links to Nature Physics: Experimental evidence for superionic water ice using shock ...
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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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2answers
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How can I get xyz coordinates of atoms of a unit cell structure from CIF format files?

I'm trying to run DFT or other 1st principle simulation of Pyrope ($\ce{Mg3Al2Si3O12)}$ and Grossular $\ce{(Ca3Al2[SiO4]3)}$ unit cell structure. So, I'm looking for unit cell xyz periodic box ...
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Difference in properties of water as ligand vs 'in lattice'

I'm trying to understand the difference in properties between water in crystals in different positions in the lattice. In this wikipedia article It quotes: Both notations can be combined as for ...
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1answer
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What is the crystal structure of bismuth oxyhydroxyphosphate (BOHP)?

The recent Chemical & Engineering News article Photocatalyst shreds drinking water contaminant PFOA report the following: Cates and his colleagues made an accidental breakthrough while testing ...
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Possibility of non-hexagonal graphene

I understand that monolayer carbon naturally forms in a regular hexagonal tiling. Is it, however, possible (if difficult) to form carbon monolayers of a different structure? A 3-12-12 tiling, for ...
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1answer
3k views

Contribution of Tetrahedral and Octahedral voids in HCP

I cannot find anywhere what the contribution of atoms situated at octahedral or tetrahedral voids in a HCP unit cell would be. I need to know this to be able to calculate the formula of a compound ...
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2answers
750 views

Sulfuric acid symmetry point group

On the following page: https://cccbdb.nist.gov/pglist.asp It appears that the point symmetry group of sulphuric acid is $C_2$. I know that $C_2$ means that there is an axis of symmetry of order 2 (180 ...
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Explain why body-centered tetragonal is a Bravais Lattice, but based-centered tetragonal is not?

Can you explain it using schematics? I think the reason is the symmetry that doesn't allowed to unique lattice points.
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charge transfer between layers of graphite with stacking fault

As a general rule, we only expect two parts of a system to have the exact same amount of charge if they are symmetry-related to each other. How much charge transfer would occur in graphite with a ...
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1answer
85 views

Why does dielectric constant of crystal fluctuates in case of Frenkel defect in a crystal?

So I was studying Frenkel defect in crystal and came across this line that said The closeness of like charges tends to increase the dielectric constant of the crystal. I'm not able to understand ...
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1answer
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Electrical resistivity [closed]

I have read that in non-metals solids the electric resistivity is reduced if we increase temperature.But this isn't logical.I mean if temperature is increased ok the electrons get extra energy but as ...
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4answers
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What is the smallest molar volume?

I wondered how small a volume a mole of material could occupy, so I started with carbon, which would need 12 grams. That's 60 carats, and there happens to be a famous 60 carat diamond. If my density/...
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1answer
166 views

Influence of the neighbouring molecules in a crystal at the example of XeF4

For reasons of symmetry I (without deeper chemical knowledge) supposed, that $\ce{XeF4}$ has a shape like $\ce{CH4}$. But according to Wikipedia its crystalline structure was determined by both NMR ...
2
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1answer
127 views

What is the crystal structure of Calcium Acetate?

I tried conducting an experiment I saw at school with some materials I had at home. The experiment consisted of mixing a solution of Acetic Acid with Calcium Carbonate to yield Calcium Acetate: $$\ce{...
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Blue color in the blue persian salt [duplicate]

Blue persian salt has tiny blue framgents. So far I could found two explanations: It is sylvinite mineral inclusions As said in Wikipedia, "The intriguing blue colour occurs during the forming of ...
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3answers
271 views

How do I know crystal structures from formula?

Give an explanation why $\ce{MgF2}$ and $\ce{CaF2}$ adopt different structure types. For example, the structure of calcium fluoride is 'fluorite' and the structure of magnesium fluoride is 'rutile'. ...
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1answer
576 views

Comparing the Lattice energy of different compounds

I am confused about some concepts related to Lattice energy. First of all,how to compare lattice energy between $2$ compounds belonging to different groups and periods? 1.Between $\ce{AlF3}$ and $\...
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1answer
94 views

Sodium Sulfate or Sodium Peroxysulfate? [closed]

In an attempt to clean drain cleaner, I reacted it with Sodium percarbonate to clean up some hardware store variety sulphuric acid. At first the reaction appeared successful, yielding a Nice Clear ...
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0answers
37 views

Gallium - Practical use to remove aluminium

Would gallium pass through aluminium into steel? The situation is two joined pieces of metal. Gallium could be applied to the aluminium to degrade it, for mechanical removal, but would it pass ...
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1answer
2k views

Shape of urea molecule around N atom

I was doing a question where I was supposed to predict the shape of the urea molecule $[\ce{H2N(CO)NH2}]$ using Lewis and VSEPR. I identified that the N atoms will have a lone pair on them and so I ...
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1answer
272 views

How to get ionic radii for coordination number 12?

I am studying $\ce{ABX3}$ perovskites, and I would like to calculate Goldschmidt tolerance factors for them. The $\ce{A}$ sites in these materials have a coordination number $12$. The Shannon's ...