A crystalline (or crystal) structure is a unique arrangement of atoms, ions, or molecules in a crystalline solid (or liquid). It is a highly ordered three dimensional structure, that reflects the intrinsic nature of its components.

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Is BCl₅ possible?

Is $\ce{BCl5}$ possible? I saw it in book. As far as we can see there is no way to get 5 chlorine atoms with boron.
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53 views

If salt crystals make a cube shape, what is this 'X' marking?

I am an amateur, with very little professional chemistry knowledge. I was doing a demonstration / experiment with my 6 year old child. We took very warm normal tap water, and dissolved into it a ...
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38 views

Chemical bonding - lattice energy

Question: Why is ionic lattice energy inversely proportional to the radius of the atom? Most heterogeneous covalent molecules are polar to some extent. The degree of polarity, or the dipole moment, ...
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12 views

Polymer Crystallinity

See the following question: I think the answer is A because of the hydrogen bond in the side group, thus the degree of secondary bonding between parallel chain segments is higher. Is my thinking ...
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40 views

How does the crystal know where to stop stacking the unit cells?

I tried to make different crystals in the cubic system by stacking cubes in a 3d software. However I need to tell the software where to skip rows or stop stacking the unit cells in a specific ...
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34 views

How do we know the size of atoms in body centered cubic system?

I'm told that in the normal cubic system there are $\frac18$ of an atom at each corner and these atoms' radius are such that $a = 2r$ ($a$ is the lattice constant, $r$ radius of an atom). In bbc ...
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Are metallic/ionic bonds weaker than covalent bonds? I was taught the opposite. Now I'm confused

In mineralogy class, I was taught that metallic and ionic bonds are weaker than covalent bonds and that's why quartz and diamond have such a high hardness value. However, in organic chemistry class, I ...
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85 views

Why do NaHCO₃ and KHCO₃ have different crystal structures?

Why do $\ce{NaHCO3}$ and $\ce{KHCO3}$ have different crystal structures? We had this in a test today and this got me stumped... My questions are: Do $\ce{NaHCO3}$ and $\ce{KHCO3}$ possess ...
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26 views

How to determine mineral properties based on chemical formula?

I need to learn a bunch of minerals and their properties. What I want is some sort of rule which helps me deduce color, crystal system, luster etc. I know that different kind of ions give specific ...
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69 views

How to memorize 7 crystal systems?

Is there any trick to memorize the angles and sides of 7 crystal systems of crystalline solids? 1. Cubic 2. Tetragonal 3. Orthorhombic 4. Monoclinic 5. Hexagonal 6. Rhombohedral or Trigonal 7. ...
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59 views

What is the minimum distance of Rubidium and Iod ions in a centered cube?

I have a problem to visualize the following assignment: What is the minimum distance between $\ce{Rb^+}$ and $\ce{I^-}$ ions if radius of $\ce{Rb^+}$ is ${1.49\cdot10^{-10}}~\mathrm{m}$ and radius ...
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482 views

How many Ga atoms are connected to one As atom in solid state Gallium arsenide

Let's start straight away. In this book on page 4 Gallium arsenide's bond structure is shown like this: $As$ is shown making $5$ covalent bonds. Recently I came across this book. The bond structure ...
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86 views

Hexagonal unit cells

I know 3 types of unit cells, the simple cubic, the body centered and the face centered. But what is a hexagonal unit cell, and why does it have a hexagon base while others are all cut into a cubic? ...
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32 views

Why is there one octahedral and two tetrahedral positions for every anion in a close packed structure?

I'm reading about ionic crystal structures with planes of close-packed anions and the interstitial sites for cations. There are two types of interstitial sites: tetrahedral and octahedral. That makes ...
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2answers
60 views

Why are cations ordinarily smaller than anions?

I'm reading on ionic crystal structures and am confused by this from my textbook: Because the metallic elements give up electrons when ionized, cations are ordinarily smaller than anions I ...
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1answer
155 views

is there any mnemonic for the AXE method?

Is there any mnemonic that helps remembering the names of the different geometries (Shapes) that we obtain from applying the AXE method ?
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114 views

How do you determine a chemical formula given the molecule's crystal structure?

How do you determine the chemical formula of a compound given its crystal structure?
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260 views

How to calculate lattice parameter only using planes and d spacing

I am trying to find lattice parameter of a hexagonal crystal, usually i uses cellcalc for calculating lattice parameter of a crystal struture. In that software it asks only two queries one is details ...
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1answer
41 views

Rapidly cooling Aluminum vapour to solid state?

What sort of a microstructure would you get on bubbling Aluminium vapors through a large tank of Helium?Would it be a glassy microstructure and/or would you get nano-powders? and/or a new crystal ...
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73 views

Bond Lengths in FCC, BCC and HCP Structures

I was wondering what the crystal structures of FCC, BCC and HCP actually look like, and where atoms are placed in their configuration? Specifically I'm looking at elemental nickel, iron and cobalt ...
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4k views

What's the difference between alpha-glucose and beta-glucose?

What's the difference between $\alpha$-D-glucose and $\beta$-D-glucose? Are they isoforms? Or do they differ in their elemental composition?
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3answers
427 views

What's up with SiO2 being tetrahedral?

If silicon dioxide tends to form a crystal lattice with four Os around a central S, why isn't the molecular formula $\ce{SiO4}$ then? I'm confused why it's unique in that its molecular formula doesn't ...
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1answer
107 views

Wasn't Rutherford's assumption of gold foil to be made of single layer wrong?

My teacher taught about Rutherford's gold foil experiment today. Sir said that, Rutherford used gold foil of thickness $10^{-7}$ m and concluded atom to be of size $10^{-10}$ m. Sir also said that ...
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288 views

What is the edge of a diamond like?

The chemical structure of a diamond is defined as an endless lattice in which each carbon atom is covalently bonded to four other carbon atoms situated at the four ends of a tetrahedron. But of ...
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16 views

What conditions to use to crystallise Equine Myoglobin?

What are the crystallisation conditions for Equine Myoglobin? I've tried repeating some from the PDB but no success.
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24 views

What does the Sm5Ge4 orthorhombic structure look like?

I see tons of papers referencing this structure but none show what it looks like.
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42 views

Why polymorphs form?

We always hear about the different arrangements of molecules that lead to the formation of polymorphs, my question here is why would a polymorph form in the first place? The material was given enough ...
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63 views

Relating a compound's radii and unit cell dimensions

We're asked often to calculate the density of a crystal, and there is a known formula for that related to the unit cell volume. Now, for simple geometric structures such as the bcc structure (and ...
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175 views

How do point defects in a crystal relate to Entropy?

I am interested in Non-Stoichiometry and how it relates to crystal structures; In particular I wish to learn about surfaces of metal oxides. I am aware that point defects in such crystals are a result ...
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548 views

Stoichiometric defects in ionic crystal?

The stoichiometric defects (Schottky and Frenkel defects) in ionic crystals are formed due to irregularities in ionic arrangement all the while maintaining the stoichiometry and electric neutrality. ...
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776 views

Is it possible to save an insoluble snowflake?

In The Big Bang Theory Season 3 Episode 1 "The Electric Can Opener Fluctuation" Leonard gives Penny a snowflake that will never melt. He said some type of chemical gas name when he try to explain, ...
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270 views

Find the number of copper spheres in a box

A box contains a mixture of small copper spheres and small lead spheres. The total volume of both metals is measured by the displacement of water to be 420 cm³ and the total mass is 5.4 kg. What ...
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528 views

Effect of dopant size on XRD peak shift

If we add an impurity atom (doping) to the crystalline struture of another material and take the XRD of the doped material what kind of peak shift can we expect. For the better description of my ...
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1answer
183 views

How much heat is required to dehydrate a hydrate?

If I have a hydrate, such as copper (II) sulfate pentahydrate, $\ce{CuSO_4 \cdot 5H_2O}$, what is the amount of heat to required to dehydrate it? I assume that it is equal to or greater than the ...
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1answer
60 views

Structure of N₅P₃?

What is the structure of the molecule N₅P₃? N₅P₃ is not documented online so could anyone please say the structure of the molecule: How many ligands does each Phosphorous atom have? How many ...
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119 views

Crystallization of solutions and liquids

The process of crystallization of a liquid or any solute occurs when its concentration exceeds the maximum concentration which the solvent can carry or when the temperature drops below the freezing ...
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176 views

Create my own solar cells?

How would I grow my own and build functional solar cells? I've read and researched that they're mostly a crystal structure of something like silicon. I would assume I'd be able to grow my own crystals ...
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1answer
125 views

How to make artificial diamond?

i always knew that carbon can not be turned to diamond artificially but while watching a video i learned that a diamond can be made from the ashes of a man , how is this possible? sorry if i put the ...
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78 views

How do octahedral seed crystals yield polyhedral Cu2O crystals?

In an article I am trying to understand, the following occurs: (summarized below) Synthesis of octahedral $\ce{Cu_2O}$ seeds:In a typical synthesis, 2.9946 g of $\ce{Cu(CH_3COO)_2}$ was dissolved ...
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769 views

Smallest nearest neighbor distance among elements

Of all the elements in periodic table, which one has smallest nearest neighbor distance? I tried searching on net, but could not find any reference. My earlier guess was one which goes into FCC with ...
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2k views

Normal Spinel and Inverse Spinel

According to my notes, [OCTAHEDRAL SITE STABILIZATION ENERGY (OSSE)], sterical effects and electronic effects in stability create a confusion in this theory. However, we are able to solve this problem ...
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1answer
61 views

Overlapping oxygens in crystal structure — what's going on?

This is a screenshot of a portion of a metal organic framework (MOF). These are two oxygens of two NMP solvent molecules. What I am wondering is why they are so close and overlapping like this. I ...
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1answer
665 views

Coordination number of CsCl (high school chemistry)

Question: Suggest an explanation for the coordination number in the $\ce{CsCl}$ lattice being different from those in $\ce{NaCl}$. Standard answer: Caesium ion is larger than sodium ion, ...
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Is diamond an allotrope or polymorph of carbon?

Is diamond an allotrope or polymorph of carbon? When is something considered an allotrope vs a polymorph?
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64 views

How can you explain that the ratio of the densities of Ag and Au equals the ratio of their relative masses?

My book says that silver and gold both have the same face centered cubic structure and then asks to show and explain why the ratio of their densities equals the ratio of their relative masses. How can ...
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302 views

Why does Naphthalene turn into needle-shaped crystals by sublimation?

I wonder why crystals of Naphthalene are needle-shaped after sublimation. Googling the fact, I could only confirm that it is true but failed to find the reason. Could someone please shed some light as ...
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1answer
223 views

Reduction and re-oxidation of TiO₂

I'm having a hard time finding data about an experiment that I know has been done a bunch of times: I have a sheet of single crystal rutile $\ce{TiO_{2}}$ (110) that I want to reduce to various ...
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1answer
2k views

Which theta should be taken from xrd pattern for calculating Scherrer's equation

We use scherrer's equation to calculate crystalline size of a particle. But which theta should we take from xrd pattern for this calculation. For example Above picture shows the diffraction ...
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Would the detaching of dendrites from electrodes in a cell, result in the crystal dissolving back into the electrolyte?

Dendrites that form on the electrodes of cells shorten the cell's lifetime, and result in reduced capacity before the end of life. If the dendrites could be detached from the electrode, would they ...
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484 views

What salts are/are not birefringent?

Is there a quick way to determine if a salt (or ionic compound in general) crystal should be birefringent from its formula without having to know/look up the crystal structure? When I'm looking for ...