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Questions tagged [bond]

For questions about chemical bonds (ionic/covalent/etc.), their properties (length, energy, angle, etc.) or their relation to other molecular properties (intermolecular forces/dipole moment/etc.). Do not confuse this tag with [lewis-structures], [dipole], [intermolecular-forces], etc.

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Why do salts such as NaCl dissolve?

If we look at solubility of salts in water, we are told that they disassociate, because the positive $\ce{Na}$ ion is attracted to the partially negative oxygen in water and the negative $\ce{Cl}$ is ...
Gerard's user avatar
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17 votes
2 answers
1k views

What utility does the tau bond model of orbital overlap have?

In his book on molecular orbital theory, Molecular Orbitals and Organic Chemical Reactions, Ian Fleming notes that Pauling formulated an early alternative model to Hückel theory for explaining the ...
Greg E.'s user avatar
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3 votes
1 answer
2k views

Why does sodium require energy to ionize?

If you look at $\ce{Na}$, it has a very low ionization energy, but the question is, why does it have an ionization energy at all? If it can get to the electronic configuration of $\ce{Ne}$, by losing ...
Gerard's user avatar
  • 3,459
16 votes
4 answers
21k views

Why is H₂O V shaped? [duplicate]

We know that the molecule of H₂O is V-shaped. This is what makes it a dipole. But why is that? I mean, if the hydrogens have a partial positive charge, then they should try to get away from each ...
Gerard's user avatar
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14 votes
6 answers
22k views

Why don't metals form covalent bonds in bulk metal?

I really don't understand why metals form metallic bonds. I mean, it makes no sense. It would make much more sense for them to form covalent bonds with themselves and have a 'pseudo-full' outer shell. ...
Gerard's user avatar
  • 3,459
1 vote
0 answers
228 views

bond energy calories

I am attempting to optimize interactions for a series of random and test molecules to a protein using docking software. The software uses QM/MMGBSA to calculate free energy in joules (yes it is not a ...
user avatar
5 votes
2 answers
994 views

Counting valency of atoms, in a molecule with python

The documentation for the indigo module can be found here http://ggasoftware.com/opensource/indigo/api#inputoutput So for instance if I have a molecule object for some SMILES string, e.g. ...
Freeman's user avatar
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2 votes
1 answer
4k views

Sigma and pi symbols in molecular orbital theory

In molecular orbitals diagram, sigma ($\sigma$) and pi ($\pi$) symbols are used. What do these symbols really mean?
Rafique's user avatar
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4 votes
2 answers
189 views

Is the electronegativity value ever used in calculations, or is it just a number assigned to each element?

Does the electronegativity only qualitatively describe bond polarity, or does it have any quantitative use? Is it possible to describe electronegativity in terms of other periodic properties, like ...
Greg's user avatar
  • 1,201
1 vote
2 answers
4k views

What is the energy released in chemical reactions?

I have heard that chemical reactions create energy. I wanted to know how this energy was created (specifically light energy) and how this energy came about. I wanted to know if the energy produced ...
kettlecrab's user avatar
10 votes
4 answers
116k views

Is melting/boiling point of ionically bonded substance higher than of covalently bound?

Is the melting and boiling point of ionic bond usually higher than covalent bond? I know that compounds with ionic bonds are usually solid at room temperature, so I want other answers than this. (...
Organ's user avatar
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1 vote
2 answers
8k views

How many valence electrons does the azide ion have?

We had a test and and we had a question asking the number of valence electrons in an azide ion, $\ce{N3^{-}}$. I find out that the answer is 16 but I could not understand how. I saw the structure. ...
ravi's user avatar
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4 votes
2 answers
3k views

Is there a word for a compound that has both ionic and covalent bonds?

For example, calcium carbide (CaC$_2$) has covalent C‒C bonds and ionic Ca$^{2+}$‒ C$_2^{2-}$ bonds.
Max Radin's user avatar
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9 votes
2 answers
7k views

What's the physicochemical difference between a chromophore and a fluorophore?

Let's take Hematoxylin, which is a pH indicator and a stain for histology, and therefore a chromophore, but does not fluoresce: Now let's take Eosin, which stains tissue pinkish, but is also ...
Eekhoorn's user avatar
  • 191
2 votes
3 answers
2k views

Avogadro - How can bonds be hidden and only show atoms?

I am using Avogadro for visualizing some cluster systems. Is there a way to hide the bonds of the system, ie. only showing atoms? Thanks!
user32004's user avatar
  • 151
2 votes
1 answer
407 views

Is energy required to form bonds [phase change]

My question is if any energy is required to form bonds, for instance when there is a phase change? If I am correct, energy might be required in the beginning, to make the reaction start and then ...
Artem's user avatar
  • 155
0 votes
1 answer
948 views

Calculating bond disassociation energy and bond energy for ATP [closed]

I'd like to calculate Bond Dissociation Energy and Bond Energy for ATP to a similar molecule. What free (at least for academic use) computer programs which natively support and document BDE? If you ...
user avatar
15 votes
3 answers
2k 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 ...
Hosenberg's user avatar
  • 151
7 votes
2 answers
9k views

Why Inductive effect operates only through single bonds?

I am not able to find any examples of the inductive effect operating through multiple bonds. Why can't electron displacement take place in multiple bonds?
Vivek's user avatar
  • 79
15 votes
2 answers
8k views

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 ...
Michiel's user avatar
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13 votes
1 answer
831 views

A theoretical molecule that could match uranium mole-for-mole

XKCD #1162 piqued my curiosity. Obviously, there's nothing we generally use as a chemical fuel that can match the energy density of uranium fission. But I wondered what it would take, hypothetically, ...
KeithS's user avatar
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-1 votes
2 answers
7k views

Why is there a charge on COOH⁻¹?

The dissociation of formic acid ($\ce{HCOOH}$) is: $$ \ce{HCOOH -> H+ + COOH-} $$ Why is there a charge on $\ce{COOH^{-1}}$ though? Is it achieved through: $$1\times(\ce{C^{4+}}) + 2\times(\ce{O^...
Johnny's user avatar
  • 9
56 votes
5 answers
10k views

How can antibonding orbitals be more antibonding than bonding orbitals are bonding?

In molecular orbital theory, the fact that a bonding and antibonding molecular orbital pair have different energies is accompanied by the fact that the energy by which the bonding is lowered is less ...
stochastic13's user avatar
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3 votes
2 answers
3k views

Predicting molecular geometry from a formula

Can someone explain the following types of molecules and predict their structure and shape? It will help my understanding if you could provide an example. ...
tom's user avatar
  • 39
2 votes
2 answers
24k views

Does SiO₂ have polar covalent bonds or coordinate covalent bonds?

First off, I know $\ce{SiO2}$ is a network solid. I am looking at its intramolecular forces between the $\ce{Si}$ and the $\ce{O}$ molecule. On the one hand, it seems to me that this should be a polar ...
Jared's user avatar
  • 29
8 votes
1 answer
50k 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 ...
Melanie Shebel's user avatar
-4 votes
2 answers
4k views

Carbon atoms in triple bonds [closed]

I was trying to know what is the probability for the carbon atoms to rotate .I know that in single bond it is 0 % and I think it is 100 % in double bond but how about the triple bond ?
user1380's user avatar
6 votes
4 answers
112k views

Covalent Bond/Hydrogen Bond

During the formation of a molecule of water ($\ce{H2O}$), what kind of bond occurs between the elements? I'm studying this subject on my own and from some sources I saw that there is a covalent bond ...
Márcio Lutz's user avatar
6 votes
2 answers
3k views

Bonding and anti-bonding orbitals in the light of time-dependent Schrödinger equation?

In organic chemistry, people draw 2p orbitals like this: and then they explain how the orbitals combine to non-bonding (π*) or bonding (π) molecular orbitals, like this: depending on whether the ...
Sampo Smolander's user avatar
-2 votes
2 answers
1k views

Effect of light on ionic compounds

If I had an ionic molecule which needed $\pu{4 eV}$ to break the ionic bond, a $\pu{7 eV}$ photon is shot at it. If it is absorbed by the molecule and breaks, where does the rest of the energy go?
user1221's user avatar
28 votes
4 answers
29k views

Carbon with 5 bonds?

I've heard that, even though according to Molecular Orbital Theory there is no chance of having nobel gases bonded to each other, it is not totally impossible. For example, under extreme conditions, ...
gunakkoc's user avatar
  • 645
3 votes
1 answer
7k views

Do metallic bonds contain London dispersion forces?

On our chemistry exam, a question asks "Which force is present between Fe particles? a) Van der Waals b) Metallic" At first it seemed obvious that it was metallic; however, upon closer reading, it ...
Leo Jiang's user avatar
  • 131
11 votes
3 answers
82k views

What is charge density?

For example, Magnesium has a higher charge density compared to Sodium, therefore its metallic lattice is stronger and it has a higher melting point. Does that mean that Magnesium has more protons and ...
Cyrus's user avatar
  • 615
1 vote
1 answer
1k views

Bent molecular geometry of water

Could you please explain how the bent molecular geometry of water is due to hydrogen bonding? I was under the impression that it was because of the lone pairs (VSEPR Theory).
LanguagesNamedAfterCofee's user avatar
11 votes
2 answers
2k views

How does localized bonding theory and hybridisation work?

So I understand molecular orbitals and how to do VSEPR models, but I seem to be struggling with understanding localized bonding theory and how to do hybridizations. After drawing the initial lewis ...
Lillie's user avatar
  • 121
6 votes
2 answers
408 views

Classical reason for good heat conductance in diamond?

My teacher in my physics course attributed this effect to phonons, more here, but I am skeptical about this argument, it feels like he is overlooking the whole question -- what about with Silica that ...
hhh's user avatar
  • 256
4 votes
0 answers
159 views

Is it okay for a sulfite ion to have 10 electrons around the sulfur? [duplicate]

Possible Duplicate: Can an atom have more than 8 valence electrons? If not, why is 8 the limit? I was watching this youtube clip ( http://www.youtube.com/watch?v=XY1XLgHUAIQ ) in which a lewis ...
DLA's user avatar
  • 151
4 votes
1 answer
2k views

Which C-C bond would break first, the one in ethane, or 2,2-dimethylpropane?

I have drawn the figures and determined intuitively that the larger molecule's $\ce{C-C}$ would break first. I made this assumption that ethane has the stronger $\ce{C-C}$ bond and I am correct, ...
Leonardo's user avatar
  • 2,168
2 votes
1 answer
2k views

Lewis structures of H₂(C)xCH₂ molecules

I need to calculate the angles between CCC, CCH, HCH in the following molecules: ethene ($\ce{H2CCH2}$), propa-1,2-diene ($\ce{H2CCCH2}$), and buta-1,2,3-triene ($\ce{H2CCCCH2}$). If I'm not ...
joshua's user avatar
  • 323
2 votes
1 answer
703 views

Lewis structures of molecules containing oxygen

As far as I know, when writing Lewis structures for molecules, we need to consider the octet rule and the valence electrons each atom has. But, if we take for example, the molecule $ Cl O_2^- $ , we ...
joshua's user avatar
  • 323
2 votes
1 answer
2k views

Why don't atoms with expanded valence shells have a formal charge?

I'm working through Chemistry - Principles and Practice, 3rd Edition and I have few complaints so I don't think it's the text. At one point, I was asked to draw the Lewis structure, with formal charge,...
readyready15728's user avatar
5 votes
1 answer
3k views

How to determine stable electron states in ionic and covalent bonds?

I'm working on a program that needs to determine if a bond between two or more elements will result in a stable state. I understand at a high-level how to fill electron subshells using the Aufbau ...
Matt Palmerlee's user avatar
12 votes
3 answers
902 views

Are there any molecules with delta bonds in their ground states?

When looking at excited states of molecules, $\delta$ bonds are relatively common, but I've never come across a molecule with a $\delta$ bond in its ground state. Are there molecules with $\delta$ ...
Dan's user avatar
  • 1,552
50 votes
5 answers
14k views

Fundamental forces behind covalent bonding

I understand that covalent bonding is an equilibrium state between attractive and repulsive forces, but which one of the fundamental forces actually causes atoms to attract each other? Also, am I ...
wolfik's user avatar
  • 695
81 votes
4 answers
42k views

Bonding in diatomic C2, a carbon-carbon quadruple bond?

Carbon is well known to form single, double, and triple $\ce{C-C}$ bonds in compounds. There is a recent report (2012) that carbon forms a quadruple bond in diatomic carbon, $\ce{C2}$. The excerpt ...
Janice DelMar's user avatar
47 votes
1 answer
12k views

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, ...
ManishEarth's user avatar
  • 15.3k
22 votes
3 answers
2k views

What is natural bond orbital theory used for?

My understanding is that the NBO methodology transforms the molecular orbital picture of a molecule into a collection of pairwise interactions (bond orbitals). This is obviously handy for didactic and ...
Richard Terrett's user avatar
19 votes
4 answers
34k views

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 ...
Juha's user avatar
  • 1,011
53 votes
3 answers
35k views

What makes banana bonds possible in diborane?

Diborane has the interesting property of having two 3-centered bonds that are each held together by only 2 electrons (see the diagram below, from Wikipedia). These are known as "banana bonds." I'm ...
jonsca's user avatar
  • 3,007
4 votes
1 answer
15k views

What is the difference between cross-linked bond and secondary bond in polymers?

In solid materials, there are two kinds of bonds between polymers: primary and secondary. Primary bonds can be also called cross-linked bonds. What is the difference between the two (strength, type, ...
Juha's user avatar
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