Questions tagged [electronegativity]

Refers to ability for an atom in a covalent framework to attract electron density to itself. Do not conflate with electron affinity, which is the ability of a lone atom (or molecule) to attract an electron to itself. Both are measured in joules/mole.

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23
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4answers
4k views

Which molecule is more acidic: CHF3 or CHBr3?

I know that fluorine is more electronegative than bromine. However, because of the size of bromine, it is more stable with a negative charge. In the case of $\ce{HF}$ vs. $\ce{HBr}$, to me, $\ce{HBr}$ ...
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What should be the oxidation state of oxygen in HOF (hypofluorous acid)?

What should be the oxidation state of oxygen in $\ce{HOF}$ (hypofluorous acid)? Sources on the internet have confused me. Most state its oxidation state to be 0, while the others state that it is -2 (...
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Why are there peaks in electronegativities in d-block elements?

Looking at the Pauling electronegativities in the Periodic Table (below, from ChemWiki): Asides from the overall trend of increasing electronegativity across and up the Periodic Table (towards ...
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Why is HF the least acidic hydrogen halide?

Fluorine is the most electronegative halogen and therefore, there is larger difference in electronegativity between the atoms of $\ce{HF}$ than any other hydrogen halide, which means the positive ...
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Electronegativity Considerations in Assigning Oxidation States

I have never seen anything other than a set of rules like these when textbooks present how to assign oxidation numbers. Such as these: However, if we keep in mind that oxidation numbers are simply ...
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1answer
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Is KF the most ionic compound?

I saw somewhere (can't recall where) that KF is the most ionic compound. I expected CsF. Does the greater polarizability of Cs allow it to more easily form covalent bonds compared to K? Does this ...
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Why are noble metals more electronegative then most metals?

I was researching about electronegativity when I looked up what a graph of electronegativity within the periodic table is. And, this appeared. I scanned it, matching up everything I knew about the ...
14
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746 views

Why is the bond dissociation energy of C-H bond higher than that of a N-H bond?

Looking at a chart of BDEs (bond dissociation energies) regarding elements bonded with hydrogen, the general trend seems to be that the BDE increases as we go to the top and to the right. This can be ...
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Why is carbon dioxide nonpolar?

I understand that polarity corresponds to an electronegativity difference and that the larger the electronegativity difference, the more polar the bond. However, I have read that carbon dioxide is ...
12
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How fast do electrons move around the nucleus?

Electrons, as we all know, are incredibly small. Smaller things do tend to move faster, right? So exactly how fast considering how small they are? Also, does the electonegativity between two atoms ...
12
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Inductive effect and hyperconjugation - one elephant, different parts?

Are the inductive effect and hyperconjugation both different ways of looking at the same phenomenon - i.e. methyl groups donate negative charge for example. Inductively we can argue that carbon is of ...
12
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Does the dipole moment increase or decrease by increasing the bond length?

It is established the dipole moment is a result of multiplication of the magnitude of charges (Q) and the distance between them (r). What I understand is that when an electron and a proton get closer (...
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How is Al2Cl6 covalent and Al2O3 ionic?

I encountered a question where the type of bonding for various oxides are prompted. Two of which are $\ce{Al2Cl6}$ and $\ce{Al2O3}$. I thought that chlorine atoms are more electronegative than oxygen ...
11
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1answer
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Why are bonds ionic when the electronegativity difference between bonded atoms is greater than 1.7?

I'm learning about how to recognise whether a bond is ionic or covalent, based on the difference in electronegativity between the two bonding partners, $\Delta \chi$. What I have now is a formula: ...
11
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1answer
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Why is electronegativity increasing with oxidation state increase?

I may be a rudimentary fact or something really "not-that-hard-to-figure-out", but In inorganic chemistry it is common to consider a single value of the electronegativity to be valid for most "...
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Does 1-bromo-4-chlorobenzene have a permanent dipole moment?

My first thought was there would be a dipole moment as chlorine and bromine are unequal in electronegativity. I have since looked up the electronegativity of both chlorine and bromine through the ...
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Inductive effect of phenyl ring

I completely understand how phenyl group 'releases' or 'donates' electron through resonance, but how is that a phenyl group shows a weak -I effect, despite having electrons literally smeared on itself?...
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Which carbon(s) in cyclohexene have the highest electron density?

I think that carbons with highest electron density will be both $\ce C1$ and $\ce C2$ because of the loosely held $\pi$-bond between them, but according to the answer given the carbons with most ...
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What happens if the electronegativity difference is exactly 2.1?

I'm learning about electronegativity in atoms and how their difference affects the type of bond they make. I know that no difference makes a non-polar covalent bond, a difference less than 2.1 is a ...
9
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1answer
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Electronegativity in krypton and xenon?

Why do krypton and xenon have high electronegativity? Noble gases are supposed to be "happy" with the amount of electrons they have, because they have 8 valence electrons (thus, most noble gases have ...
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1answer
12k views

Why a higher s character increases a carbon atom's electronegativity?

To make us understand certain phenomenon like the higher acidity of alkynes than alkanes and alkenes, our teacher told us to learn this as a general rule: Higher s character leads to a more ...
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1answer
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Hydrogen halide acidity

Why is it that $pK_{\ce{a-HF}} \lt pK_{\ce{a-HCl}}\lt pK_{\ce{a-HBr}}\lt pK_{\ce{a-HI}}$, although the electronegativity decreases? The more electronegative the atom accompanying hydrogen, the lower ...
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Why does ozone have an electrostatic potential map similar to that of SO2?

This is the electrostatic potential for ozone. This is the electrostatic potential for sulfur dioxide. (Click to enlarge) They look almost exactly the same except one is all oxygen atoms and the ...
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1answer
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Why and when are bonds broken

I am new to chemistry (I have only done a GCSE in it) so forgive me if I am missing something obvious. But I am trying to very roughly simulate some chemical reactions. My background is in Artificial ...
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Why is HCl not considered to have hydrogen bonding?

A molecule that has hydrogen bonding usually follows these two premises. 1.) There is a hydrogen atom involved 2.) Hydrogen must be bonded to a highly electronegative element which are ...
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1answer
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Why does C=O have a larger dipole moment than C-O?

Why does $\ce{C=O}$ have a larger dipole moment than $\ce{C-O}$? According to me, dipole moment directly depends upon bond length and electronegativity difference. In $\ce{C=O}$ and $\ce{C-O}$, (I ...
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Strongest negative inductive effect group between trimethylammonium, ammonium and dimethylsulfonium groups

Which of the following group exerts the strongest -I effect? $\ce{-N(CH3)3+}$ $\ce{-NH3+}$ $\ce{-S(CH3)2+}$ $\ce{-F}$ My idea is that positive species exerts more -I effect than ...
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Lithium batteries a reality - why not sodium, pottasium batteries?

Lithium batteries seem to be mainstream now, offering high energy density, high output current capability. Stepping down the periodic table there are alkali metals with greater electronegativity than ...
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Allred-Rochow vs Pauling Electronegativity scale

While observing the trends in electronegativity of the elements, I found a discrepancy between Allred-Rochow and Pauling scales. In Pauling's scale, chlorine is the third most electronegative element (...
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Is the inductive effect always measured relative to hydrogen?

Wikipedia has defined the Inductive effect thus: "In Chemistry and Physics, the inductive effect is an experimentally observable effect of the transmission of charge through a chain of atoms in a ...
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Reference for electronegativities of different metal oxidation states

A long time ago I was researching the effect of the self regulatory response in Fe and Co. I found that my results made sense based on the idea of the electronegativity of the ions considered. I found ...
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1answer
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Why is the electronegativity of hydrogen 2.20?

Well, I was doing research about the ways we can measure electronegativity and I just realized there must be an arbitrary electronegativity set for an specific element to give us the relative amounts ...
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1answer
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Why does attractive forces of nucleus increase more than shielding across groups?

When you study the electronegativity of the elements, the general trend is that it rises with increasing group number, and decreasing period. Supposedly this is because the attractive forces of the ...
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Is it possible to calculate electronegativity of surface atoms?

As the title asks, is it possible to calculate the electronegativity (EN) of specific atoms on extended surfaces (slabs), more specifically using computational methods? There are a few issues here I ...
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Why does NF3 have a smaller bond angle than NH3?

I've already read many answers about the reason why $\ce{NF3}$ has a smaller bond angle than $\ce{NH3}$ , but I can't seem to understand them. Here's my understanding of the situation: $\ce{NH3}$: ...
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Why is zinc more reactive than copper?

In terms of electronegativity, from what I understand electronegativity increases going across the period, so surely this should mean that zinc less readily loses its outer shell electrons than copper?...
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1answer
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IChO problem involving the condensation point of NF3, NHF2, NH2F

This is a problem from the 2016 International Chemistry Olympiad (IChO): Which of $\ce{NF3}$, $\ce{NHF2}$, and $\ce{NH2F}$ condenses at the lowest temperature? The answer book says that it is $\ce{...
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Structures for NO+ (Nitrosonium)

There are two possible structures for Nitrosonium : In the first structure, there is a +1 Formal charge on Oxygen, whereas, In the second structure, there is a +1 Formal charge on Nitrogen. Q. ...
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Why is energy released as electrons move?

Why is it that energy is released from electrons when they move from one atom to a more electronegative one?
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Why are the electronegativities of transition metals so similar to each other?

I was wondering why the electronegativity among transition metals are so similar. I can't find anything on the internet, just vague answers about the d orbitals that don't seem to provide a sufficient ...
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1answer
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Is there a mathematical formula for electronegativity?

If we lost all the numerical values we have for the electronegativity of elements, is there any mathematical formula that can be used to re-calculate them based on proton (and neutron) numbers alone? ...
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1answer
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Electron distribution in a C-S bond

My lecturer said that in a $\ce{C-S}$ bond, sulfur is slightly $\delta^{-}$ and the carbon slightly $\delta^{+}$, although they have (almost) the same electronegativity. What is the cause of this ...
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Difference between electropositivity and electronegativity

Sodium is more electropositive than hydrogen although they are in the same group. Why is the electronegative value of hydrogen greater than sodium (metal)?
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1answer
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Which is more electronegative: hydrogen or astatine?

Which is more electronegative - hydrogen or astatine? I'm a bit confused because my teacher taught me that for an atom to be electronegative it has to be on the top of the periodic table and/or on the ...
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1answer
661 views

Using electronegativity and atomic size to compare acidity of cysteine with serine

In proteins, the alcohol group of serine is generally more difficult to deprotonate than the thiol group of cysteine. Serine and cysteine respectively: In the literature, the explanation given is ...
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1answer
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Relation Between Degree of Hydration and Electropositivity

Why are salts of strongly electropositive elements less heavily hydrated in aqueous solution than the those of less electropositive elements? Shouldn't it be the other way round as the salts of ...
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1answer
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Comparing Acidic Strength of H3PO4 and H3AsO4

The $pKa$ values for H3AsO4 and H3PO4 are $2.30$ and $2.12$ which indicate that H3PO4 is a stronger acid compared to H3AsO4. I looked up their electronegativity values to find that they are almost the ...
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Which is more electronegative: chlorine or nitrogen?

Why nitrogen is considered to be less electronegative than chlorine. Nitrogen should be more electronegative as I was reading some content about this and I read some reasonable arguments: $\ce{NCl3}$ ...
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2answers
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Why is solid sodium hydride a base and not an acid when reacted with water?

When solid $\ce{NaH}$ is mixed with water, the products are not $\ce{Na-}$ and $\ce{H3O+}$. The reaction yields $\ce{NaOH}$ and $\ce{H2}$ gas. Why does solid $\ce{NaH}$ not act as a Brønsted acid in ...
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1answer
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What is the most polar covalent bond?

Which polar covalent bond of the following: Cl-F S-O P-N C-Cl It's trivia - I guess. And I got it wrong. Electronegativity list was given for the following: F, O, Cl, N, S, C, H, P My wrong ...