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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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1answer
26 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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3answers
382 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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1answer
62 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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0answers
25 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
52 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
102 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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0answers
83 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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0answers
183 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
34 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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0answers
66 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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1answer
2k 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
220 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
91 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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2answers
165 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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1answer
14 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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2answers
22 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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1answer
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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1answer
53 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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1answer
118 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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353 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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1answer
577 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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1answer
258 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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1answer
362 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
166 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
54 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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1answer
105 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 ...
2
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2answers
167 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
120 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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0answers
69 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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1answer
666 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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3answers
1k 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
55 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
501 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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2answers
722 views

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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1answer
61 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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1answer
263 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
216 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
1k 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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0answers
26 views

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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1answer
433 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 ...
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1answer
1k views

When we heat a borax crystal, why does it first expand and then contract?

In the borax bead test, we take a crystal of borax and then heat it. A small loop is made in the end of a platinum or nichrome wire (as used in the flame test) and heated in a Bunsen flame until ...
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2answers
1k views

How do copper sulphate and the like change crystal structure on adding water of hydration?

Copper sulphate, in its hydrated form, is crystalline, whereas the anhydrous form is amorphous. Gypsum has a similar story-- on heating the crystalline dihydrate we get an amorphous hemihydrate. ...
4
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1answer
185 views

Are these two space groups in a group–subgroup relationship?

Given two crystal space groups, how can one determine if they are in a group-subgroup relationship? The specific case at hand is P 21/m 2/m 2/a (aka P m m a, #51) and P m m 2 (#25), but knowing how to ...
5
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2answers
138 views

What is it about the relationship between the Fe2+ and Fe3+ in magnetite that makes it diamagnetic?

Hematite is composed of $\ce{Fe2O3}$, and is paramagnetic, whereas magnetite is $\ce{Fe3O4}$ and is diamagnetic. Magnetite's nature is due to the presence of both $\ce{Fe^{2+}}$ and $\ce{Fe^{3+}}$ ...
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1answer
80 views

Is there a theory behind selecting elements that may be successful in potential superconductors?

Looking at something like $\cf{ YBa{_2}Cu{_3}O{_7}}$ which was one of the first cuprate superconductors to be discovered, I'm always curious how the selection of these substances as likely ...
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3answers
658 views

How does NaCl maintain its crystalline structure?

My understanding is that $\mathrm{NaCl}$ is an ionic compound, in which $\mathrm{Cl}$ becomes (effectively) $\mathrm{Cl^-}$ and $\mathrm{Na}$ becomes $\mathrm{Na^+}$. So I understand why I would get a ...