What is Electronegativity: Definition and 45 Discussions

Electronegativity, symbolized as χ, is the tendency of an atom to attract shared electrons (or electron density) to itself. An atom's electronegativity is affected by both its atomic number and the distance at which its valence electrons reside from the charged nucleus. The higher the associated electronegativity, the more an atom or a substituent group attracts electrons. The opposite of electronegativity is electropositivity: a measure of an element's ability to donate valence electrons.
On the most basic level, electronegativity is determined by factors like the nuclear charge (the more protons an atom has, the more "pull" it will have on electrons) and the number and location of other electrons in the atomic shells (the more electrons an atom has, the farther from the nucleus the valence electrons will be, and as a result, the less positive charge they will experience—both because of their increased distance from the nucleus and because the other electrons in the lower energy core orbitals will act to shield the valence electrons from the positively charged nucleus).
The term "electronegativity" was introduced by Jöns Jacob Berzelius in 1811,
though the concept was known before that and was studied by many chemists including Avogadro.
In spite of its long history, an accurate scale of electronegativity was not developed until 1932, when Linus Pauling proposed an electronegativity scale which depends on bond energies, as a development of valence bond theory. It has been shown to correlate with a number of other chemical properties. Electronegativity cannot be directly measured and must be calculated from other atomic or molecular properties. Several methods of calculation have been proposed, and although there may be small differences in the numerical values of the electronegativity, all methods show the same periodic trends between elements.
The most commonly used method of calculation is that originally proposed by Linus Pauling. This gives a dimensionless quantity, commonly referred to as the Pauling scale (χr), on a relative scale running from 0.79 to 3.98 (hydrogen = 2.20). When other methods of calculation are used, it is conventional (although not obligatory) to quote the results on a scale that covers the same range of numerical values: this is known as an electronegativity in Pauling units.
As it is usually calculated, electronegativity is not a property of an atom alone, but rather a property of an atom in a molecule. Properties of a free atom include ionization energy and electron affinity. It is to be expected that the electronegativity of an element will vary with its chemical environment, but it is usually considered to be a transferable property, that is to say that similar values will be valid in a variety of situations.
Caesium is the least electronegative element (0.79); fluorine is the most (3.98).

View More On Wikipedia.org
  1. P

    Does high electronegativity mean low electropositivity?

    I understand that electronegativity and electropositivity are opposite terms, but does being high in one mean you are low in the other? I saw that HCl will react with NaCl to create Cl2 and NaH. I believe that Cl has the greatest electronegativiy (willingness to attract an electron). So...
  2. C

    Can Covalent Bonds form between atoms with no electrons?

    Homework Statement I learned that Covalent Bonds form between different specific atoms ( with similar electro-negativity ) with electrons. However, I wondered what type of bond would form between the different atoms if they had no electrons? Also , if I have 2 atoms with similar...
  3. Wrichik Basu

    A new scale for electronegativity

    Electronegativity has seen a number of scales throughout its years of existence. Starting from the Pauling scale to the Allen scale, Wikipedia has a long list. Recently, Martin Rahm, Tao Zeng and Roald Hoffmann have defined a new scale for electronegativity. The news has been published in...
  4. Physics345

    Electronegativity / predicting structure / ranking order

    Homework Statement a) Calculate the differences in electronegativity between the elements in each of these compounds. I)CaBr2 II) Na3N III) CH4 b) Predict whether each of these compounds would be an ionic or a molecular compound and justify each prediction. c) Rank the bonds in these compounds...
  5. L

    Rank Electronegativity Pairings

    Homework Statement Br2, KBr, and HBr Homework Equations none The Attempt at a Solution I understand that Br2 would be least electronegative because they both equally share the electrons, but i don't understand why KBr is more electronegative than HBr. This question was on my quiz, and i...
  6. V

    Polarity and Electronegativity

    Homework Statement When to use electronegativity value? and when to look at both bonds and shape? Homework EquationsThe Attempt at a Solution This isn't really a question more so need some clarification. First question is about electronegativity and bond polarity. When placing the delta...
  7. G

    Electronegativity and electron affinity?

    Why is the electronegativity of fluorine higher than chlorine but not electron affinity? How is it possible that it has a stronger attraction towards a bonding pair of electrons than when a new electron is added to the atom?
  8. G

    Classic Static Electricity Balloon Example

    Homework Statement 1. Explain why a balloon sticks to a wall after being rubbed on your shirt (remember the wall is not metal and does not have "free" electrons") 2. Include a balanced force diagram that includes the electrical force and gravitational force (assume electrical force is twice...
  9. PWiz

    Does electronegativity affect rate of entropy increase?

    Let's say we have two samples of pure Helium-4, and two other samples of pure hydrogen fluoride (consisting of Hydrogen-1 and Fluorine-19) all in separate containers. One container of each chemical is at the same initial temperature of 200°C at a pressure of 101kPa, and the other ones are at...
  10. psuedoben

    Why do xenon/krypton have relatively high electronegativity

    what sets xenon and krypton apart from the other noble gasses that enables them to have higher electronegativites?
  11. D

    Why isn't there any friction in magnet trains?

    Hi there, first poster here. Something has been boggling me and I cannot seem to find the answer anywhere. I really hope that you will help me =) A magnet train in vacuum has no friction whatsoever, right? Then what about electron interactions between the 'rail' and the train itself due to...
  12. C

    Validity of the Pauling Scale of Electronegativity?

    I propose the Pauling Scale is not valid in all circumstances, and other scales of electronegativity would do better to predict the behavior of electron density in molecules: Electronegativity seems to be poorly defined for such a widely used chemical property: a 'tendency' of an atom or...
  13. A

    Calculating electronegativity differences

    Hi, everyone! Just a quick question to be sure: I want to calculate the electronegativity difference of Na_{2}O,\ \Delta X_{Na_{2}O}, Is this correct: \Delta X_{Na_{2}O}=X_{O}-X_{Na} Or is it: \Delta X_{Na_{2}O}=X_{O}-2*X_{Na} (since there are 2 Na atoms).
  14. P

    The Inductive Effect and Electronegativity

    According to my A level Chemistry textbook, the presence of the O atom in a C=O bond in any carboxylic acid (CH3COOH, for instance) pulls the electrons towards it causing the O-H bond to "weaken", thereby making the molecule more susceptible to dissociation, or in other words, accounts for the...
  15. C

    Wool vs Cotton - electronegativity?

    Hi, If you rub woll against cotton, the cotton get's negatively charged and the wool positively charged. IS this because the atoms of the cotton are more electronegative? Or is it because the electrons of the wool attoms are more loosely held?
  16. 3

    Effects of electronegativity on the bonding on an ionic compound? AgBr

    Homework Statement Use the concepts of electronegativity and polarisation to interpret the bonding in AgBr Homework Equations I have always understood electronegativity as the ability of an atom in a molecule to attract a pair of shared electrons towards itself. So this would usually...
  17. S

    Series of Electronegativity Questions

    Hi! I would like to know if what I'm thinking is correct. Please help me as to I'm confused :cry: 1. If atom "X" has a high Electronegativity, then that means that it can take Electrons from atom "Y" with a low Electronegativity easily causing atom "X" to have a more negative charge "-" and...
  18. D

    Is a Reaction with Slight Electronegativity Difference Still a Redox Reaction?

    does a reaction involving transfer of an electron between atoms with slight difference in electronegativity still count as a redox reaction?
  19. M

    Electronegativity vs electrochemical series

    Carbon is higher in the electrochemical series than hydrogen, which indicates it is more electropositive, but Pauling values show carbon as more electronegative - 2.55 vs 2.2!? Any reason / explanation for the apparent contradiction? Tried looking for an Eo value for C (should be more...
  20. S

    The Electronegativity of Ions?

    Homework Statement "Rank the following in the order of increasing absolute electronegativity: F, Li, Ti4+, P, H, C, Mg2+, Li+." Homework Equations The Attempt at a Solution - I can rank neutral species no problem. Periodic table has that covered, and Pauling values are easy to...
  21. H

    Electronegativity and stability of ions?

    I've just started a course on organic chemistry and the professor said some things which did'nt exactly make sense to me: 1) In a period, atoms are more electronegative as we go to the right. The more electronegative an atom is, the more stable it becomes. 2) In a group, atoms increase...
  22. K

    Chemistry On Molecular Geometry of Hydrazine and Electronegativity

    Homework Statement 1. What is the molecular shape of Hydrazine N2H4 w.r.t. N atom? 2. H2S and H2O, which one has a larger bond angle? 2. The attempt at a solution 1. Trigonal Pyramidal is the answer given. But Hydrazine has 5 atoms around its central atom and I'm unable to fathom...
  23. AakashPandita

    Polarity in water molecule and electronegativity of oxygen in that molecule.

    H20 is polar in nature. It is fundamentally because oxygen is more electronegative than hydrogen and the shared electrons tend to be near oxygen. This may be because the atomic number of oxygen is more than that of hydrogen. But in the bond I don't understand how the 2 shared electrons...
  24. R

    How does electronegativity affect bond strength?

    How does electronegativity affect bond strength? whats the strongest bond polar covalent, nonpolar covalent, or ionic how does electronegativity affect bond strength some people say the more electronegative the molecule the stronger the bond, so than shouldn't ionic bonds be stronger than...
  25. B

    Why is Gold's High Electronegativity Misleading in its Natural Occurrence?

    Gold has rather high electronegativity. If that is the case then why does it often appear in nature in its pure form? I would think it would be attracting a lot of molecules and binding with other elements.
  26. N

    Does Electronegativity Vary in Different Bonded Atoms?

    i wanted to ask this…. 1. if an atom forms a bond with some atom of different element,say C-O ,then since O attracts elec more ,can we say tht it now it has less electronegativity compared to only O? 2. in a tertiary carbon why do electrons get pushed towards the central C,is it because of...
  27. R

    What is the Correct Electronegativity Values for Defining Bond Types?

    I recently found a table of electronegativity differences, where certain differences where used to define certain types of bonds. However I found different values at different sites so I wonder if someone could help sort this out. Link 1...
  28. Saitama

    Quick help needed, How electronegativity is related to polarising power?

    Homework Statement I was studying about electronegativity from a book. Its written that as polarizing power increases, electronegativity increases. Also, the electronegativity increases as the s-character in the hybrid orbitals increases. I don't understand these two statements. I don't...
  29. T

    Can someone explain electronegativity, please.

    I'm taking AP Bio and we're covering basic chemistry needed for it. I've not had chemistry yet, so I'm left wondering about the interesting stuff, like electronegativity. Basically, what I'm interested in, is: why is H2O polar? What is it about O that makes it magnetically attract H...
  30. K

    How to determine the value of electronegativity

    for an atom that is an element in Period 4 , Group 7 to compare with another atom of element in Period 3, Group 5 Without looking at the Periodic table or electronegativity values, how can I determine which one of these two atom is more electronegative? (While Period 4, Group 7 has...
  31. S

    Can electronegativity be the same for 2 elements?

    Between Sulfur and Iodine, which has more Electronegativity? I read that they both have the same, if so how can i determine in SI2 compound around which atom do the shared electrons spend more with with(Since that is determined by which atom has greater electronegativity) Or maybe they spend...
  32. T

    Why is Trifluoroacetic Acid more acidic than Trichloroacetic Acid?

    Can anyone explain concisely why Trifluoroacetic Acid is more acidic than Trichloroacetic Acid, but HCl is more acidic than HF?
  33. A

    Fajan's Rules and Electronegativity

    Hey friends, I am having some confusion regarding covalent character of ionic bonds (Fajan's rules) and polar character of covalent bond (electronegativity and dipole moments). We apply Fajan's rules when we start a bond to be purely ionic, as in NaCl, and derive it's partial covalent character...
  34. L

    Does ionisation energy depend on electronegativity?

    Because, if a higher electronegativity means a higher attraction to electrons an atom has, wouldn't that mean that a greater energy would have to be put into ionise an atom with a higher electronegativity?
  35. Z

    Is Electronegativity Applicable to Ions?

    Is there any method to compare the electronegativity of ions such as O-, N+, S-, O+?
  36. R

    Electronegativity difference NaH

    Although the electronegativity difference between sodium and hydrogen in NaH is less than 1.7 , it is ionic bond WHY??
  37. D

    Chemistry- electronegativity and bonding

    the temperature for the following to reach a pressure of 100mmHg is as follows(celcius)) HI -> -72.1 HCl -> -114 HBr -> -97.7 HF -> -28.2 how can this be? since they are all combinations of H and an element of the last column before the noble gas surely the smaller the size of the...
  38. N

    Acidity Across Periods: Does Electronegativity Matter?

    So acidity increases across a period because the electronegativity of the conjugate base increases as move from left to right. This means it can better stabilize the negative charge. Something else that contributes to this trend is the fact that as move from left to right across a period, the...
  39. M

    Why Does Electronegativity Decrease Down a Group?

    [SOLVED] Electronegativity Confusion Homework Statement Looking at the periodic chart and going down, the electronegativity goes down, ie Na = .9 and K = .8 From the definition electronegativity is the ability to attract electrons. So is that to say the more electronegative would actually...
  40. P

    Electronegativity and element identification

    As part of the exploration of one of the moons of Jupiter, a probe digs under the surface, where it finds a pocket of gas. It starts to do some on-board experimentation. The data stored in the probe's computer include the following table of Mulliken electronegativity values of gases. Element...
  41. S

    Electronegativity and dipole moments

    is there a relationship between the two? its been bugging me for a while. can't find the answer.
  42. A

    NH2- vs. H-: Electronegativity and Basicity

    Why is NH2- a stronger base than H-. I would think that due to N's greater electronegatavity, it would want to hold on to its electrons more, making it less basic.
  43. C

    Carboxyl acid strength and electronegativity How do they relate?

    Carboxyl acid strength and electronegativity... How do they relate?? Here is a question that I had on a recent chem II exam. Which is the strongest acid? A. CH3COOH B. CF3COOH C. CCl3COOH (Cl for chlorine, not Carbon 13) D. CBr3COOH E. CI3COOH I selected choice A because the...
  44. S

    How do chemists measure electronegativity?

    How do chemists measure electronegativity? Thanks, -Scott
  45. S

    Electronegativity & Oxyanions: Exploring ClO-, IO3-, BrO3-, NO3-, & PO4 3-

    Is there any theory as to why you have ClO-, ClO2-, ClO3-, and ClO4-, but only IO3- and BrO3- ? And why is there no FO3- ? I suspect this has something to do with electronegativety but I'm uncertain. And how come you have NO3-, but PO4 3-?