12 votes

Why does chlorine have a higher electron affinity than fluorine?

The electron being gained by fluorine would be taken in to a much smaller 2p orbital and requires more electron coupling energy than that of much larger 3p orbital of chlorine. Therefore, energy ...
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  • 121
8 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 ...
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  • 29.6k
8 votes

Is there a relation between the ionization energy and the electron affinity?

Okay, here's what I did (and I highly encourage everybody to do this along with this tutorial-style answer, just so you get the feel for prepping and looking at data from the world wild web). Data ...
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  • 10.5k
7 votes

is it possible to break the bonds of diatomic elements such as fluorine or iodine and create positive and negative ions by electron bombardment?

Sure, why not. It's just the question of your bombarding electrons having the right energy. At low energies, a bombarding electron will likely be captured by one of the iodine atoms: $$ \ce{I2 + e- -&...
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7 votes
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While electrolyzing concentrated aqueous sodium chloride, why is it that chlorine is discharged but not sodium?

Let's take a look at a table of standard electrode potentials and find the relevant half-reactions: Reductions (there is also a half-reaction for water reduction that doesn't involve a proton at -0....
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7 votes

Why does K have a greater electron affinity than Ca?

Neither K nor Ca "wants" to ionize. Both ionization energies are endothermic. This question refers to eelctron affinity, which is gaining an electron. K has a more exothermic electron affinity ...
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  • 3,760
6 votes
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Which atom goes in the middle of a lewis dot structure?

ETA: I'm unclear about your question. Are you asking why nitrogen isn't the central atom or why sodium isn't? If it's the former, the explanation is below. If it is the latter, sodium, then it's ...
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6 votes
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Ca energy release when gaining an electron

Two sign conventions: (1) the more common one states that a positive electron affinity value represents energy release when an electron is added to an atom; (2) the other states that a negative ...
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  • 38.8k
6 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 ...
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  • 65.6k
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 ...
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  • 4,835
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 ...
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  • 2,070
5 votes

Why is electron gain generally exothermic?

Energy of electron in vacuum is zero. If it can attach (however weakly), the energy is gained and process is therefore exotermic. It is not an atom which releases energy, it is the whole system. ...
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  • 4,417
5 votes
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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 ...
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  • 38.2k
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 $...
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  • 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. ...
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4 votes
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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 ...
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4 votes
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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 ...
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  • 16.7k
3 votes
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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 ...
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3 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 ...
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3 votes

Can we add an electron to an atom?

F-center defects in crystals are due to unpaired electrons and can be caused by ionizing radiation; these defects can accumulate over thousands of years. This can be used to find the age of minerals ...
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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 ...
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3 votes
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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 ...
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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 &...
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2 votes
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Electron Affinity trends

After rediscovering my own question, I'm posting it as an answer for anyone else to reference or to correct. Electron affinity (EA) refers to "the energy released when an atom in the gas phase ...
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  • 1,078
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 $n=3$ ...
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  • 1,879
2 votes

For group 7 elements, are anions a lower energy state than being neutral atoms?

Yes, the electron affinity for group 17 elements (group VII by older IUPAC nomenclature) is generally exothermic, so the uptake of an electron should be favourable. But as Ivan mentioned in a comment,...
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  • 63.6k
2 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 ...
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  • 34.7k
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 ...
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  • 12.2k
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 ...
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2 votes
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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 $E_1$...
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