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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8
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3answers
26k views

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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2answers
5k views

Which relatively simple molecules violate the octet rule?

I'm learning how to draw Lewis diagrams. Everything I've read emphasizes the octet rule. However, to the best of my knowledge, that rule only applies to elements in the first three periods. On our ...
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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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1answer
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Are long oxygen molecules possible?

Are large oxygen containing molecules possible? Either large rings, or chains with hydrogen atoms at the ends. Like this: $\ce{H-O-O-O-O-O-O-O-O-O-$\cdots$-O-O-O-O-O-H}$
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What is the difference between “molecular mass”, “average atomic mass” and “molar mass”?

I don't understand the difference between "molecular mass" and "average atomic mass". They seem like the same thing to me. Is it that average atomic mass is just the weighted average of the "weights"/...
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4answers
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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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2answers
8k views

How to know whether s-p mixing will happen in heteronuclear molecules?

How do I know whether s-p mixing would occur in some diatomic heteronuclear molecules like CN, CO, NO etc?
12
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5answers
11k views

Is there a way to use free software to convert SMILES strings to structures?

So far I've been unsuccessful in finding an open source tool that will convert a large number (>100k) of SMILES strings to a chemical structure. Is this really only solved by commercial applications? ...
5
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1answer
427 views

How can we confirm the number of protons in an atom?

The periodic table tells us that there are 6 protons in a carbon atom. Is there a way to verify this first-hand? Or are we just expected to believe it unquestioned?
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4answers
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Do symmetric hydrogen bonds in neutral molecules exist?

As far as I know, there have only few truly symmetric hydrogen bonds been observed. Unquestionable is the existence of it in the bifluoride ion, $\ce{[F-H-F]-}$, see also here. There are a couple of ...
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5answers
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Can fluorine act as the central atom in interhalogen compounds?

Why can't fluorine be the central atom in inter-halogen compounds? A $\ce{F-F}$ bond is weaker than a $\ce{F-X}$ bond and thus, fluorine should be happy to form inter-halogen compounds. But, why ...
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1answer
1k views

Do alkali metals not form diatomic molecules?

I know hydrogen forms a diatomic molecule $\ce{H2}$, where the electronic configuration of hydrogen is $\ce{1s}$. But why doesn't lithium also form a diatomic molecule? Its electronic structure is $\...
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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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How do noble gases bond with themselves?

Noble gases have full electron shells, which virtually blocks any other element from bonding with it. However, I've heard about cases where they bond to each other - for example, helium can ...
4
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3answers
683 views

What are dipole moments in a molecule supposed to act upon?

In a $\ce{CO_2}$ molecule, a total of four electron pairs are shared between the carbon and oxygen atoms, such that 2 pairs are shared between the carbon atom and each oxygen atom. Oxygen has a ...
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3answers
2k views

What does 'organic/non-organic molecule' means exactly? [duplicate]

I am new to the organic chemistry world. I was delving for the exact answer to my question, and I've found some results: In wikipedia (french), is was mentioned that an organic molecule contains ...
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2answers
20k views

Why is an S-S bond stronger than an O-O bond?

I'm wondering why exactly the single bond between two sulfur atoms is stronger than that of two oxygen atoms. According to this page, an $\ce{O-O}$ bond has an enthalpy of $142~\mathrm{kJ~mol^{-1}}$, ...
20
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4answers
428 views

How to explain the concept of mol and reactions involving mol quantities

From time to time I do little pro bono lessons for second grade in math, physics, and chemistry. Recently I came across this question. In a container is $2~\mathrm{mol}$ of $\ce{SO3}$ (sulfur ...
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8answers
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Are there any good examples of commonly ingested molecules that contain particular toxic individual elements?

In the house on my own and an article popped up on my feed with the following statement: While the Government has insisted the chemical is safe, cadmium is recognised as a cause of lung cancer ...
11
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4answers
17k views

Why do people still use the mole (unit) in chemistry?

I know that the mole is widely used in chemistry instead of units of mass or volume as a convenient way to express amounts of reactants or of products of chemical reactions. I'm wondering why people ...
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2answers
74k views

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 ...
11
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1answer
1k views

What makes a compound a dehydrating agent?

When a carboxylic acid with low molecular weight is heated with $\ce{P2O5}$ we get the corresponding anhydride. My book says that this reaction happens with dehydrating agents such as $\ce{P2O5}$. I ...
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What actually is the Wavefunction?

I am aware that the square of the Wavefunction gives the probability density of finding an electron at a particular point in space. I have also heard that it's a complex number but since it's a ...
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1answer
479 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
3k views

Why do methane molecules have 15 degrees of freedom?

I've just been learning a little thermal chemistry including the equipartition theorem. As part of this, my textbook discusses how to figure out the degrees of freedom for different chemicals. The ...
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1answer
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Why doesn't EDTA have a double bond?

EDTA (Ethylenediaminetetraacetic acid) has a structure like this But why, as the name 'Ethylene' suggests, doesn't it should have a double bond between carbons?
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2answers
290 views

Molecule with 13 total electrons

Is there a stable molecule with total number of electrons equal to 13? Molecule can be either organic or inorganic
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1answer
11k views

Is the proper formula for phosphorus oxide(V) P4O10 or P2O5?

I would like to ask about formula of phosphorus oxide(V). Should it be $\ce{P4O10}$ or $\ce{P2O5}$? Which is right when I have to write the molecular formula?
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3answers
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Identifying the number of bonding and lone pairs without a dot and cross diagram

I've just learned how to predict the shapes of molecules in class today using VSEPR theory. I would like to ask is there anyway to find the number of bond pairs and lone pairs without drawing a dot-...
0
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1answer
131 views

Atomic properties [closed]

This may be a very broad question. I always asked myself how scientists manage to find out the exact molecular structures of for instance water or carbohydrates. How do they know? How do they know the ...
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3answers
1k views

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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4answers
12k views

Is a diamond a single molecule?

Assuming a perfect diamond with no impurities. Would this diamond considered to be a single large molecule? Browsing the interweb I found several opinions about this but did not find a clear Yes or No....
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1answer
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Is this a possible explanation as to why sigma bonds are stronger than pi bonds?

Sigma bonds form due to the axial overlap of two orbitals whereas pi bonds form due to their lateral overlapping. Since the former is more effective, we can say that sigma is stronger than pi. We mean ...
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3answers
2k views

Proper typography of “NOx”

I am a journal typesetter, and recently I came to a problem that I'm not sure I know to solve. The question is how to properly typeset the "NOx" abbreviation for nitrogen oxides. Which is ...
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1answer
2k views

What makes water a liquid (when it is)?

I'm curious about what the minimal conditions for some collection of water molecules to be liquid water are. What is the minimum number? What sort of bonds must hold? What other sorts of things I don'...
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3answers
8k views

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 ...
8
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1answer
41k views

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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4answers
35k views

Why is tetrafluoromethane non-polar and fluoroform polar?

Consider the Lewis dot structures of the molecules fluoroform, $\ce{CHF3}$, and tetrafluoromethane, $\ce{CF4}$:   My first line of thought is that both of these molecules are symmetrical (the ...
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0answers
380 views

Measure the complexity of a molecule

Back in April, there was an article in new scientist discussing the work of Lee Cronin, who postulated that molecules of a certain complexity must be biological. Cronin has developed a way to ...
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1answer
22k views

Stereo Isomerism - syn/anti

I was studying the types of stereo-isomerism E-Z, Cis-Trans and then I come across syn-anti stereo-isomerism this one is giving me a bit of fight in understanding, especially where lone pairs are ...
6
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3answers
2k views

How was the diatomic nature of many common gaseous elements originally determined?

How did scientists find out that $\ce{Cl2, H2, O2}$ atoms have a two-atomic molecular structure ?
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2answers
21k views

How to determine polarity in large molecules?

In case of small molecules like water things are more or less clear, but when I see a large complex molecule like Thyroid Hormone - how should I find out that this molecule is non-polar?
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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?
3
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1answer
171 views

How to change CO₂ to a less polluting gas?

I want to change $\ce{CO2}$ coming out of the tailpipe of a car to some other compound that is considerably less harmful to the environment with a filter of some sort. What are some ways that this is ...
3
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2answers
11k views

Why does ammonia have sp hybridization?

Apparently it has $sp^3$ hybridization, but I don't understand why. Ammonia ($\ce{NH3}$) seems to me to not require $sp$ hybridization because all of its bond lengths are already equal. It has 3 ...
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2answers
8k views

How to find out oxidation state when compound has multiple electronegativities

How do I solve for oxidation state in something like CH3-O-F? The fluorine is more electronegative than the oxygen which is more electronegative than the carbon which is more electronegative than the ...
24
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1answer
2k views

Why do the atoms in molecular models have the colors they have?

Molecular models are a great tool for visualizing a molecule in three-dimensional space. These models even appear on the web (practically every chemical's Wikipedia page), and there is a very specific ...
12
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1answer
614 views

How does the pyramidalization effect the bonding angles in a distorted octahedral environment?

This is a follow up on "Generally Octahedral - Meaning?". Since Dissenter asked in the comments to my answer: I'm not sure why the $\ce{F_{eq}-S-F'_{eq}}$ bond angles would be compressed, even if ...
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1answer
2k views

Electrolysis of Beer

Electrolysis of water, means that the water is separated into hydrogen and oxygen. As beer also includes water, I initially thought electrolysis of beer would cause the water to separate, and the ...
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1answer
1k views

How is a side-group that contains a double bond named?

In my chemistry lecture, we are working on the naming and nomenclature of organic molecules. When we got to the naming of alkenes and alkynes, we were told that the functional group had to be in the ...