What is Electron affinity: Definition and 30 Discussions

The electron affinity (Eea) of an atom or molecule is defined as the amount of energy released when an electron is attached to a neutral atom or molecule in the gaseous state to form a negative ion.
X(g) + e− → X−(g) + energyNote that this is not the same as the enthalpy change of electron capture ionization, which is defined as negative when energy is released. In other words, this enthalpy change and the electron affinity differ by a negative sign.
In solid state physics, the electron affinity for a surface is defined somewhat differently (see below).

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  1. S

    Chemistry Electron Affinity: Adding Electrons to Valance Shells

    I think that an electron adds up in the valance shell of an atom because an atom tends to achieve the nearest noble gas configuration. But I don't understand how and why electron enters the valance shell. Energy is released when an electron adds up in the valance shell. But why is energy...
  2. sneakycooky

    Is this a good alternative definition of electron affinity?

    traditional definition of electron affinity: the amount of energy released by an element in its gas form when gaining an electron second definition?: the stability gained by an element in its gas form when gaining an electron (e.g. halogens are more stable after gaining an electron, and when...
  3. prakhargupta3301

    Between O- and F- which has higher electron affinity?

    O-- 2s2 2p5 F-- 2s2 2p6 (Fully filled hence more stable.) Since F- is fully filled as compared to O- wouldn't it require more positive electron gain enthalpy to gain one more electron than O-? However, the correct answer is given (A) Please tell me how. Thank you for reading.
  4. L

    [College Chemistry] Electron Affinity and Ionization Energy

    Homework Statement Here's the pic of the problem and my work The Attempt at a Solution I'm not sure how I'm suppose to calculate the energy change? Did i do it correctly in the picture? For number 9, I just added IE1 and IE2 and subtracted EA1 to get a total of 3200.3. This means that the...
  5. NuclearBoofluff

    Why electron affinity of noble gas is endothermic?

    Homework Statement Why is the EA of Neon endothermic even though it has a high Z eff? Basically, what makes a full valence shell so stable? The attempt at a solution I know it has to do with shielding, core e-, and valence e-. But I don't know how to word it.
  6. 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?
  7. Titan97

    Why is electron affinity positive?

    I was reading thermodynamics and about Born Haber cycle. There, I found that the values given for electron affinity are positive. When an electron is added to flourine, it attains noble gas configuration. So i t becomes more stable. So shouldn't the reaction be exothermic?
  8. A

    Electron affinity, work function, band gap

    What exactly is the relation between these 3 quantities? As far as I can tell the work function is the energy needed to bring an electron from the fermi level out into vacuum, while affinity is from the bottom of the conduction band. Does this then mean that they can be used to calculate the...
  9. H

    Ionization and electron affinity

    I am confused about Ionization and electron affinity concept If energy is Required to add the electron to gaseous atom (Electron affinity - in case of noble gases) Then why further energy is required to Remove it? (Ionization energy) isnt this violation of Conservation of energy?
  10. G

    Chemistry Calculate the Electron Affinity of F(g) in kJ/mole using Hess' Law?

    Homework Statement Calculate the Electron Affinity of F(g) in kJ/mole using Hess' Law. IE1 + IE2 of Sr(g) is 1580 kj Hsub of Sr(s) is 144 kJ Hdiss of F2 is 79 kJ Hf of SrF2 (s) is -1215 kJ Hlatt of SrF2 (s) is -2441 kJHomework Equations | | \/ The Attempt at a Solution 1. Sr(g)+Sr+(g) ->...
  11. mishima

    Electron Affinity, Type of energy released?

    This might be a dumb question, but for instance when oxygen gains an electron to become an anion, energy is released equal to its electron affinity. What exactly is the form of this energy? Is there a photon of a certain wavelength emitted? Does the anion slow/cool down because of the small...
  12. Q

    Puzzle about electron affinity in solid-state physics

    Hi everyone, I am a student studying semiconductors and solid-state physics. I have a question which is haunting for several years. That is about the definition of electron affinity in solid-state physics. Its definition in solid state physics may be quite different from that in chemistry...
  13. S

    How Does Electron Affinity Relate to Energy Release in Gaseous Atoms?

    What is electron affinity?? Q: Why energy is released when an electron is added to a gaseous atom? What is electron affinity? Please explain it with reference to release of energy?
  14. Z

    Electron affinity and electron gain enthelpy

    Hello, I was wondering if someone might be able to explain these terms. Specifically, the difference between them. From what I have read they seem to describe the same thing, i.e. the enthalpy change involved in: X(g) + e- → X-(g) I am sure there is a difference that I am just not...
  15. P

    Ionization Enthelpy, Electron Gain Enthelpy and Electron Affinity

    Ionization Enthalpy is defined as the amount of energy required to remove an atom's electron (can be valence or consecutive) ... this definition doesn't sound so complex. The definition of Electron Gain Enthalpy - it is the amount of energy required to add an electron. But, what is Electron...
  16. J

    Understanding electron affinity

    Hello everyone, I am learning some chemistry and have come across a topic that I cannot get my mind around. I understand that electron affinity is the energy given off/absorbed when an electron is taken in by atom. Atoms with low ionization energies tend to have low negative/positive...
  17. P

    Ionization Energy / Electron Affinity Systems

    Homework Statement We have two atomic systems, Na+ + Cl- (System A) and Na + Cl (System B), where all the particles are separated in the infinite distance. Which system (A or B) is higher in energy? Describe the energy difference of the two systems by ionization energy and the electron...
  18. O

    Which Ion Has a More Negative Electron Affinity: Na+ or Cl?

    Hi guys, my first post/question. Excuse my stupidity if you think this is an easy question, I'm really having a difficult time with reviewing this part in general chemistry. Homework Statement Which has a more negative electron affinity, Na+ or Na? Na+ or Cl? 2. The attempt at a...
  19. L

    Understanding Ionization Energy, E- Negativity, and Electron Affinity

    Electro Negativity, Ionization Energy, and Electron Affinity... Can anyone explain these to me in normal English please? I am having a hard time understanding these concepts from the definitions given in the book and from my teacher. Thank you.
  20. E

    Electron Affinity: Does It Increase Across Periods?

    Does electron affinity increase across the period, and decrease down the group?
  21. M

    Semiconductor Electron Affinity

    Hi There, Im doing a study of MOS capacitors (Semiconductor is 4H-SiC) and I am looking at the interface trap density with respect to temperature (range 300K to around 600K) and also photonic excitation with hv<Eg. That said, i have a question regarding the temperature dependence on...
  22. T

    Why does chlorine have a higher electron affinity than fluorine?

    Homework Statement By a general rule the electron affinity of elements increases from left to right along the period and decreases down a group. Then why does chlorine have more electron affinity than fluorine even though it is below fluorine in the periodic table? Homework Equations...
  23. Borek

    What is the definition of electron affinity in solids?

    I was always under impression that electron affinity is defined (and listed in tables), as energy change when isolated atom in gaseous phase gains an electron. However, I was lately told that the same term is used for solids in "standard semiconductors references", like in Sze's Physics of...
  24. N

    Chemistry- Electron Affinity very confused

    Homework Statement Rank the atoms in electron affinity, from smallest to largest. Homework Equations none The Attempt at a Solution G has the highest energy, followed by H then K. I looked at the diagram and saw that- G= 1s^2 2s^1 (Li) H= 1s^1 (H) K= 1s^2...
  25. H

    Why Can't Classical Theory Explain Electron Affinity?

    My lecturer writes the following in his lecture notes: “ Electron affinity: a QM property of atom to attract an electron, and increases the number of electrons required to complete the outer electron shell decreases. “ I have known electron affinity as the desire, so to speak, of an atom to...
  26. L

    Chemistry question on electron affinity

    Homework Statement under the same conditions which one of the following atoms will liberate the largest amount of energy when it gains an electron? 1.Na(g) 2.Ar(g) 3.Li(g) 4.N(g) 5.Mg(g) Homework Equations The Attempt at a Solution I was told the answer's N 'cos it's the...
  27. P

    Electron Affinity descripton.

    I have been looking at websites on electron affinity. My notes report it as 'energy released when an atom gains an electron. Wikipedia http://en.wikipedia.org/wiki/Electron_affinity says the amount of energy released when detaching an electron from a singly charged negative ion,[1] i.e., the...
  28. R

    Why is Electron Affinity Negative for Period 2 & 3 Elements?

    Why is electron affinity negative? In my book its written, that on moving down a group, tit decreases. But why is it that period 3 elements have greater E.A. than period 2 elements?
  29. O

    MgO Electron Affinity: Why is O +737 kJ?

    I have a problem with MgO(s). Mg(s) → Mg(g) Heat of sublimation = +148 kj ½O2(g) → O(g) Bond dissociation = +249 kj Mg(g) → Mg2+(g)+ 2e- IE1+IE2= +2201 kj O(g)+2e- → O2- EA= +737 kj look at the EA in peiodic table O(EA= -141 kj). When O charged 2e- it seems to be like F(EA=-328...
  30. jimmy p

    Why Chlorine has Higher Electron Affinity than Fluorine

    Just a quickie, why does Chlorine have a higher electron affinity than fluorine, when fluorine is the most electronegative element in the periodic table?? I asked my chem tutor but she didnt really explain much.