Questions tagged [allotropes]

Different forms of an element which exist in the same state but have different molecular or crystalline structures. Classic examples of allotropes include diamond and graphite (allotropes of carbon), red phosphorous and white phosphorous, and $\ce{O2}$ and $\ce{O3}$ (allotropes of oxygen).

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Why is octaoxygen diamagnetic?

I tried considering that according to LCAO-MO theory $\ce{O2}$ is paramagnetic, which is confirmed by experimental evidence. Since octaoxygen has the crystal structure in figure, I thought there is a ...
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Why does the stratosphere have a lot of ozone, but not the Earth's surface?

Ozone ($\ce{O3}$) and dioxygen ($\ce{O2}$) are both allotropes of oxygen. However, nearly 90% of all ozone is found in the stratosphere, whereas near the earth's surface (or overall in the troposphere)...
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Is ozone paramagnetic?

This answer shows why ozone should be diamagnetic. Still, Wikipedia article says it is weakly paramagnetic, having positive magnetic susceptibility $χ = \pu{+6.7E−6 cm^3 mol^-1}.$ There's a paper ...
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Are coke (solid fuel from coal) and charcoal same thing obtained from different sources?

As coke is obtained from destructive distillation of coal, and charcoal from destructive distillation of substance other than coal (like wood and animal bones), are both the same thing, with charcoal ...
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Why do some elements form allotropes and others do not? [duplicate]

I just studied in my chemistry class about the allotropes of carbon. But why does carbon form allotropes? Also why only carbon? Why do some elements form allotropes and others do not?
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Stability of α, β, γ allotropes at different temperatures

While reading about elements or compounds I often come across allotropes (or forms) being referred to as α, β, γ forms. Examples: Sulfur has two allotropes: α rhombic and β monoclinic. Out of these ...
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Which allotropes of sulfur exist naturally?

I'm writing a paper on chemistry and I would like to know which allotropes of sulfur exist naturally. I've searched on the Internet but I haven't found anything about natural sulfur allotropes except ...
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What is "activated red phosphorus"?

[WP = white phosphorus ; RP = red phosphorus ; ARP = activated red phosphorus] A YT channel, Extraction & Ire has a video from two years ago (2018) on converting WP to RP by keeping the former in ...
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Predicting sign of enthalpy of allotropic transition of phosphorus

How to predict the sign of enthalpy during the transition $$\ce{P(s, white) -> P(s, red)}?$$ $\ce{P(s, red)}$ is more stable than $\ce{P(s, white)}$ due to release in angle strain. Since during ...
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Can other group IV elements form graphene analogs with interesting properties? [duplicate]

Graphene has gathered quite a bit of press due to its unique physical properties which hold enormous promise in a wide range of applications from semiconductors to high strength materials. Given that ...
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Se+P White or red P?

I read this in an old chemistry book. It says: When selenium is dropped into melted phosphorus, it dissolves rapidly, and the compound sinks through the liquid phosphorus in red streaks. My ...
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What is tetrasulfur like? Why is there so little experimental information about it?

Phys.org's How sulfur helped make Earth habitable before the rise of oxygen says Mapping the bonds and vibrational modes of molecules containing sulfur isotopes is helping to shed light on the ...
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why is white phosphorous given to have ZERO standard heat of formation [duplicate]

why is white phosphorous given to have ZERO standard heat of formation?? while it is well known fact that white phosphorous is highly reactive and is obviously less stable than red and black ...
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Does a neutral dimercury molecule exist?

Is a neutral $\ce{Hg2}$ molecule possible, as a gas under extremely low (partial) pressures? What is the enthalpy of formation or similar? It is my impression that usual mercury vapors are monatomic? ...
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Why does diamond have no molecular formula?

Why does diamond have no molecular formula, while buckminsterfullerene does have it, despite both being allotropes of the same element?
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Calling Diamond an element?

Is it scientifically correct to call Diamond an element? Carbon has a wide range of allotropes, so would it be correct to actually just call graphite, diamond etc an element. For that matter, could we ...
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Why does ozone have higher entropy than oxygen?

$$\ce{3O2(g) -> 2O3(g)} \qquad \Delta H^\circ (\pu{298 K}) = \pu{+142 kJ mol^-1}$$ Since the RHS of the equation contains less number of gaseous molecules, naturally I expected the $\Delta S$ to ...
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Polycyclic nitrogen network?

So today I suddenly stricken with this structure and started to wonder if this polymeric structure of nitrogen is possible or not? If possible then what's its stability?
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Allotropes of hydrogen

Is it possible to chemically bond 8 hydrogen atoms together to form an allotrope like $\ce{H8}$?
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Does sulfur have various allotropes at room temperature?

Recently I had a question in my chemistry test that said: Which of the following nonmetals does not have multiple allotropes at room temperature? A) Oxygen B) Hydrogen C) Sulfur D) ...
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Aside from carbon, what other substances can be made "superhard"?

So diamonds are an allotrope of carbon, that is formed when carbon is put under immense pressure, right? What other elements or compounds can you make into "diamonds", as in more durable, harder ...
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Are allotropes of sulfur two different phases?

Monoclinic sulfur and rhombic sulfur are two allotropes of sulfur. In phase equilibria, part of the system that is having distinct boundary, mechanically separable and different chemical or physical ...
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Solubility of white phosphorus

Why is white phosphorus soluble in $\ce{CS2}$ but red phosphorus not? Is it something in relation with the structures of both? Please explain.
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Are nuclear spin isomers "allotropes"?

In my book there's a question: Does $\ce{H2}$ show allotropy ? Describe its allotropes and their applications. Wikipedia doesn't list any allotropes of $\ce{H2}$. However, when searching on the ...
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Is Changing between Allotropic forms a Physical or Chemical Process?

When a substance changes its alloptropic form, is this considered a physical change or a chemical change? Right now, I am thinking that it would depend on what the change was. For example, if ...
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Is ozone really a chemical element? [closed]

In our chemistry book is written that ozone ($\ce{O3}$) is a chemical element. Also our chemistry book gives a definition that agrees with that. But our teacher doesn't agree. His reasons: If ...
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Which elements exhibit allotropy?

I was just reading this article about allotropes which relates allotropy with some specific elements and also this wiki article. Also some other articles some of which relate allotropy with catenation ...
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Allotropes of Phosphorus

Something I noticed whilst revising about group 15 is that the darker the allotrope of phosphorus, the more stable it is. white/yellow – very volatile, soluble, pyrophoric red – air ...
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Why do we not see silicon in a structure like graphite?

Silicon exists in a structure similar to diamond, with 4 silicon atoms bonded to each other in a tetrahedron. Why do we not see it exist in a structure like graphite? Is it even possible to get ...
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7 votes
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Which allotrope of phosphorus is kinetically the most stable?

Which allotrope of phosphorus is kinetically the most stable? I ruled out white and yellow as being quite reactive. Red and black allotropes are both polymeric and comparitively less reactive. ...
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Allotropy and polymorphism

Polymorphism is defined as the ability of a solid material to exist in more than one form or crystal structure, whereas allotropy is defined as the property of some chemical elements to exist in two ...
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Allotropy in Nitrogen and Bismuth of Group 15

Which elements of Group 15 of the periodic table have allotropes? P, As and Sb have well-known allotropes: P: White, Red and Black; As: Yellow, Black and Gray (Grey); Sb: White, Yellow and Black....
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Can powdered beta-tin be made from raising the temperature of alpha-tin?

When white tin ($\beta$-tin) is cooled to a temperature below $13.2\ \mathrm{^\circ C}$, it creates the allotrope of gray ($\alpha$-tin), a gray, amorphous powder. My question is that once you have ...
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Does single-layered Aluminium Phosphide exist?

I'm currently working with the band structure of graphene and graphene-like compounds. α-Boron Nitride (hexagonal, single layer) has many interesting properties. I was wondering if the next period ...
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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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Why does sulfur, but not oxygen, catenate?

Oxygen is a rather boring element. It has only two allotropes, dioxygen and ozone. Dioxygen has a double bond, and ozone has a delocalised cloud, giving rise to two "1.5 bonds". On the other hand, ...
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