Questions tagged [molecules]

An electrically neutral entity consisting of more than one atom (n > 1). Rigorously, a molecule, in which n > 1 must correspond to a depression on the potential energy surface that is deep enough to confine at least one vibrational state. This tag should be applied to question about certain molecules or a class of them.

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1answer
710 views

Why can't you see air but can feel it [closed]

Is there a device that can measure the air in the room in lbs? I would appreciate the anseer
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Why do molecules having a higher relative molecular mass have stronger inter-molecular forces?

Why do molecules like alkanes with higher relative molecular mass ($M_\mathrm r$) have stronger intermolecular forces? For example, methane ($\ce{CH4}$) has a weaker intermolecular force than pentane (...
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Egg-Detection in Pastries: An Analysis in Heat-Alterated Molecule Identification

I would like to know if anybody here knows of a method to detect the presence of ovalbumin--or any unique, egg-related molecule, in a baked good. Here I am anticipating that the "unique egg-related ...
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1answer
478 views

Methylcyclohexane chair conformers

I am trying to create the molecule of the methylcyclohexane in the equatorial and axial conformers. I read in this site about the chair conformation. My molecule looks like the following picture (...
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1answer
516 views

Percentage of a conformer in vacuum

I just started with Molecular dynamics simulations. My background is computer science but I'm learning about scientific computing and thus my jump into MD. Having said that, I was asked to calculate ...
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1answer
869 views

Quantity of Carbon and Hydrogen according to the molecular formula

$1.367$ of an organic compound containing carbon, hydrogen and oxygen was combusted in a stream of air to yield $3.002$g of $CO_2$ and $1.640$g of $H_2O$. The molecular mass of the compound was found ...
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3answers
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When did the atom Theory Become indisputable?

We know that the Greeks were the first scientists (or better, philosophers) to introduce the idea that matter is made up of little “chunks”, and they named these chunks “atoms”. This idea that matter ...
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1answer
490 views

Do halogens bond more commonly with each other or themselves?

To me it seems like diatomic elements like $\ce{F2}$, $\ce{Cl2}$, etc. occur more prevalently than diatomic molecules with both, like $\ce{ClF}$. Is this the case, and if so, what causes diatomic ...
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1answer
303 views

Prediction of surface atoms in molecule from its graph

If we are given a molecular graph i.e. al the atoms involved and their connectivity, how can we make reasonable prediction if the atom would lie in the surface or in the inner part. On way might be ...
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Electron density definition of single, double, triple bonds?

I was reading this question and the answer by user EricBrown to it, and this got me thinking about covalent chemical bonds. The way I was always taught is that a single bond contains 2 paired ...
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Approximation of electron density of a small molecule

Starting point for Quantum Theory of Atoms in Molecules (AIM) is the electron density $\rho(r)$. It could be determined experimentally (X-ray diffractions). I want to know how can we estimate them ab ...
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Polar group strong dipole effect molecular axis

There are some fundamental charactaristics of liquid crystal. One of them is that all liquid crystals are organic compounds and at one side of their long molecular foundation there exists a polar ...
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2answers
492 views

How different are molecule with same connectivity

Let us represent molecules by graphs (atoms are vertices and bonds are edges). Let $A$ be the adjacency matrix of the molecular graph. $A_{ij} = b$ where $b$ is either binary: 0 when atom i and j are ...
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How to get the valencies of elements?

How to find the valencies of elements by using its distribution of electrons? Please explain the method in simple words. Do you have to study the valencies or is there a simple way of remembering? PS:...
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1answer
786 views

Number of bonds in a Lewis Structure [duplicate]

I'm asked to find the Lewis Structure of sulfuric acid, $SO_4H^-$. After struggling for a while, I sumply looked it up. How can this be? Sulfur has 6 electrons in its valence shell, so it should ...
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1answer
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How does the reaction Mg + O₂ → MgO occur? [closed]

$\ce{Mg + O2 → MgO}$ Magnesium, oxygen and magnesium oxide form the above equation. How? What do I need to learn to do this? atomic numbers/ valencies?
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Molecular orbital theory & predicting the stability of a molecule?

A question in my general chemistry textbook gives me a list of formulas for molecules and ions. It then asks me to determine, using molecular orbital theory, whether or not each would exist in a ...
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1answer
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How long can polyethylene molecules be?

In this video, Steve Spangler says the substance he is using (a polyethylene oxide): http://www.youtube.com/watch?v=m-88M75_PCI He mentions that one molecule would go to the moon and back twice! I ...
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2answers
5k views

Tool that generates electrostatic maps of molecules?

Do you know any tools that generate electrostatic potential 2d maps of the molecules as an image?
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1answer
181 views

How to calculate weight of CO₂ in one kg of fuel

I'm trying to do homework and I have the answers to the problems but I can't read the explanation because it's illegible and I can't find how it's done in my notes. Here's the simplest example: $$\...
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Why do single elements in a molecule have an oxidation state of zero?

For example, take $\ce{O2}$. The oxidation state of oxygen is -2, yet once its in a molecule its oxidation state becomes zero? How is this so?
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1answer
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How can one find products when one knows the reagents?

I'm going to use an example (I could have used a different one); On the document it is about the study of the chemical balance of an acid-basic solution. The chemists have written the chemical ...
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4answers
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Differences between H-H-O and H-O-H

I'm not an expert. In simple words how do they differ: $\ce{H-H-O}$ and $\ce{H-O-H}$ molecules?
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Law of Multiple Proportions: What is the significance of small whole numbers?

I'm new to Chemistry and in my textbook, it describes the Law of Definite Proportions (aka Proust's Law) and then goes on to describe the Law of Multiple Proportions. The example they give is carbon ...
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How do the molecules know the future? How do they proceed to form “Most Stable” compound?

I'm tutoring few students for Chemistry. During the course, I many times use the phrase "Out of these possibilities this one is stable. So it is formed". I get questions like, "How do the molecules ...
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Can magnesium chloride absorb water and ammonia at the same time?

Anhydrous magnesium chloride will absorb ammonia to the tune of ($\ce{Mg(NH3)6Cl2}$). Incidentally, magnesium chloride is usually a hexahydrate ($\ce{MgCl2(H2O)6}$) at STP. My question is, could ...
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269 views

Has the molecular diatomic oxygen trianion been observed or predicted?

Has diatomic oxygen ever been observed with a 3− charge, i.e. $\ce{O_2^{3-}}$? Have any ab intio calculations been done on this ion? Update: Just to summarize some of the answers below and add my ...
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1answer
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Why do single, double and triple bonds repel each other equal amounts?

I'm here to share with you something that totally confuses me, as I can't see the logic behind it, and my teacher doesn't know either. Let's take a set of bonds that's trigonal pyramidal, with a lone ...
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1answer
229 views

Find empirical formula when individual masses are known

I'd like to illustrate my question with an example: Imagine nickel reacts with fluoride and you start with $0.766\ \mathrm{g}$ of nickel, an unknown amount of fluoride and you end with $1.261\ \...
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1answer
458 views

Shape of C₂H₂ molecule

What is the shape of the $\ce{C2H2}$ molecule? The fact that is has a triple covalent bond between the 2 carbon atoms and 2 other bonding pairs between the hydrogen and carbon atoms leads me to ...
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1answer
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Why not “Oxygate” OO4(2-)?

So many atoms can be surrounded by oxygen atoms to make anions - chromate, phosphate, etc. In particular there's Tellurate $\ce{TeO4^{-2}}$, Selenate $\ce{SeO4^{-2}}$ and Sulfate $\ce{SO4^{-2}}$ - ...
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What makes a molecule a polyatomic ion?

I checked the Wikipedia page, but it did not seem to provide a very intuitive explanation. What distinguishes a molecule such that it behaves like a polyatomic ion? I understand that it is a ...
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3k views

Is there any scenario in which the size of a molecule increases due to an increase in temperature?

Take an ice cube for example. Heat is applied in a closed container until it is vaporized completely. Will the molecule's size be larger (on average)? Is there a substance that you know of that has ...
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1answer
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Do noble gasses besides Helium form diatomic molecules at low temperatures?

I know that at extremely low temperatures (mK and lower), Helium can form diatomic molecules. Do the other noble gasses also form molecules at extremely low temperatures?
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What is the difference between physical and chemical bonds?

If you characterize the chemical bonds to two categories physical and chemical bonds, how do you do it? Aren't all bonds chemical and physical? From the freedictionary.com, chemical bond: Any of ...
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Why do different substances have different boiling points?

For example, why does for example oxygen turn into gas at a much lower temperature than water? Does it have anything to do with the molecular structure? A water molecule does have a more complex ...

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