Skip to main content
9 votes

Why don't gases of elements with negative electron affinities exist as ions in nature?

It totally does not work like that. You can't say that $\ce{2F^-}$ is less stable (or more stable) than $\ce{F2}$; you can't compare them at all. People would say "B is more stable than A" when there ...
Ivan Neretin's user avatar
  • 31.2k
8 votes

Are 1st Electron Affinities positive or negative?

This is sadly, one of those matters of "convention" that chemistry is so plagued by. For most neutral atoms, the magnitude of $\Delta H$ for the following reaction is negative (i.e. energy is ...
orthocresol's user avatar
  • 71.4k
5 votes

If fluorine has a lower electron affinity than chlorine, why does it have a higher ionization energy?

To quote chemguide: The first ionisation energy is the energy required to remove the most loosely held electron from one mole of gaseous atoms to produce 1 mole of gaseous ions each with a charge ...
DHMO's user avatar
  • 5,035
5 votes

Why don't gases of elements with negative electron affinities exist as ions in nature?

So consider a vessel wherein which we have Fluorine atoms (F) in gaseous state. Now, they have seven outer shell electrons and would really love to get the 8th one for an octet. What would have to ...
IT Tsoi's user avatar
  • 2,118
5 votes

Why do alkali metals have an exothermic electron affinity?

I think you mean to ask about the electron affinity of the alkali metals. That is, the enthalpy gain or lost when adding an electron to an atom. While the electron affinity for alkali metals are much ...
Geoff Hutchison's user avatar
5 votes
Accepted

Why is Electron Gain Enthalpy of only Be and Mg positive, in group 2?

The presence of $d$ orbitals can indeed provide a means for otherwise closed-shell atoms of alkaline-earth metals to accept electrons. Wu et al. [1] describe carbonyl complexes of Ca, Sr, and Ba in ...
Oscar Lanzi's user avatar
  • 58.6k
5 votes
Accepted

Are there any monocations with negative electron affinities known?

A monocation with an endothermic (negative) electron affinity is the same as a neutral species with an exothermic (negative) ionization energy. Reframing it this way may turn up more information. The ...
Nicolau Saker Neto's user avatar
4 votes

Electron affinities of the chalcogens and halogens

The amount of screening is the same in the two groups but the effective positive charge that the incoming electron feels is stronger in Group 7. For instance, oxygen has the electronic structure of $...
rbw's user avatar
  • 461
4 votes

Why is electron gain generally exothermic?

Looking at the comment thread above, I believe a bit more elaboration can help, so here it is Why is electron gain generally exothermic? Think of a unit positive sphere and a unit negative sphere. ...
Gaurang Tandon's user avatar
4 votes
Accepted

2nd Electron Affinity of halogens

Chart of Electron Affinities The Electron Affinity can be thought of as the "electrical advantage" given by adding an electron to an atom. So, if you have a halogen that gains an electron, it ...
Hanry Hu's user avatar
  • 618
4 votes
Accepted

If Oxygen has a lower electron affinity than Sulfur, then why doesn't sulfur has a lower electron affinity than selenium?

This is likely due to second period elements' being quite small, so electron-electron repulsion is much more significant than in a third period element. The general trend is that EA is more positive ...
Zhe's user avatar
  • 17.5k
4 votes

Are there any monocations with negative electron affinities known?

You are talking about superalkalis, which are defined as groups of atoms that have a lower ionization energy than any alkali metal atom -- that limit being about 3.9 eV for caesium. ("Pseudo-...
Oscar Lanzi's user avatar
  • 58.6k
3 votes

Why do atoms have electron Affinity?

Actually, not all atoms are stable, at least not in the gas phase, which is where we measure the electron affinity. You should first read Why do atoms "want" to have a full outer shell? for ...
Gaurang Tandon's user avatar
3 votes

Relation between electron gain enthalpy and electron affinity

You are correct, at absolute zero $Δ_\mathrm{eg}H^⦵ = - A_\mathrm{e}$ for the gas-phase act of gaining an electron: $$\ce{X(g) + e-(g) → X-(g)}$$ $$A_\mathrm{e} = E(\ce{X(g)}) - E(\ce{X-(g)})$$ The ...
andselisk's user avatar
  • 38.1k
3 votes
Accepted

What exactly is lattice energy?

In summary: IE and EA are just partial terms in the formation enthalpy of solid ionic compounds, that includes also LE and atomization enthalpy of elements. Their values alone can give a hint, but do ...
Poutnik's user avatar
  • 42.3k
3 votes
Accepted

On a periodic table it shows that Zn and Cd and Hg all have 0 electron affinity. Why is that?

They all have 2 electrons in their highest occupied s sublevel and 10 electrons in their highest occupied d sublevel (both sublevels are full). As a result, they can not complete any orbitals by ...
Joseph Hirsch's user avatar
3 votes

Why do alkali metals have an exothermic electron affinity?

After taking one electron ns2 orbital is fulfilled and become stable. So Alkali metals has negative electron gain enthalpy.
Somesh Banerjee's user avatar
3 votes

Why is there not a strict correspondence between electronegativity and ionic character?

Lots of materials show a bonding character different from what would be expected from electronegativity difference alone. Here are a few: • Hydrogen fluoride has an electronegativity difference ...
Oscar Lanzi's user avatar
  • 58.6k
3 votes
Accepted

How can chlorine be 'only' the third-most electronegative element yet have the highest electron affinity?

Electronegativity is a rather slippery thing, really. Roughly speaking, it depends on both electron affinity (the tendency to take on a negative charge) and ionization enthalpy (the tendency not to ...
Oscar Lanzi's user avatar
  • 58.6k
3 votes
Accepted

Why do selenium , tellurium and polonium have more negative electron gain enthalpy than oxygen?

Electron Gain Enthalpy becomes less negative down the group. This is true, as a general trend. But the 2nd period is an exception to this trend. In p block, it is observed that the EGE of some 2nd ...
WhySee's user avatar
  • 445
3 votes

Why is Electron Gain Enthalpy of only Be and Mg positive, in group 2?

A simple, intuitive answer based solely on high-school chemistry and available emperical data; 1s < 2s < 2p < 3s < 3p < 4s < 3d For Be, all the orbitals up to 2s are filled, so the &...
Kanghun Kim's user avatar
3 votes

Most stable monoatomic ion of nitrogen

The correct answer is: Both nitrogen(-III) and nitrogen(-I) are unstable (with respect to electron ejection) per se, and exist in ionic crystals only due to the lattice energies outweighing the energy ...
Kanghun Kim's user avatar
3 votes

Why is the first electron affinity exothermic and successive ones endothermic?

Electron affinities are generally smaller than ionization energies. $\pu{IE_{\ce{Na}} = 5.14 eV}$ but $\pu{EA_{\ce{Cl}} = 3.61 eV}$ If the electron clouds had been fully spherical symmetric and fully ...
Poutnik's user avatar
  • 42.3k
2 votes

Which element has a greater second electron affinity, sulfur or oxygen?

The most important fact here is that the electron added to $\ce{S-}$ goes into an $n=3$ orbital ($3p$), whereas the one added to $\ce{O-}$ goes into an $n=2$ orbital ($2p$). The larger $n=3$ ...
user213305's user avatar
  • 1,929
2 votes

What exactly is lattice energy?

A picture is worth a thousand words. In the picture above, start with a mole of solid sodium and half a mole of Cl$_2$ gas, in the ground state. Then gasify the sodium with 107.3 kJ of heat, then ...
James Gaidis's user avatar
2 votes

Regarding comparison of ionization energies

When you talk about the ionization energy of $\ce{Mg^2+}$, it is the third ionization of $\ce{Mg}$, which is equal to $\pu{7734 kJ/mol}$. When you talk about the ionization energy of $\ce{Ne}$, it is ...
Mathew Mahindaratne's user avatar
2 votes
Accepted

Find the Ionisation Potential and Electron affinity of X

The Ionisation Energy of an atom is defined as the minimum amount of energy required to remove the most loosely bound electron of an isolated neutral gaseous atom or molecule. In this case, since $E_1$...
Aniruddha Deb's user avatar
1 vote
Accepted

More Anti-bonding or less bonding electrons?

Both (N2)+ and (N2)- have same bond order of 2.5 but (N2)+ would be more stable as it has lesser number of electrons leading to lower inter-electronic repulsions.It can also be said that (N2)- has ...
James's user avatar
  • 26
1 vote

Electron Gain Enthalpy

The main question here is "why is it exothermic". The following diagram illustrates the conundrum: This portrays a ball rolling over a track. Thanks to energy conservation, in frame 2 the ball has ...
Buck Thorn's user avatar
  • 22.4k
1 vote

Why do Hydrogen Halides(with the exception of HF) form mostly strong acids?

I would like to correct a few points firstly that the halide part is not negatively charged. Also the electronegativity of the halide is the dominating effect in this case. Hydrofluoric Acid as we ...
Sidharth Giri's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible