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Girls Vs Boys Chemistry Challenge!

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Reply 20
Original post by JMaydom
Clues coming up!!!

It's to do with how well the ligand can donate electron density to the metal ion.


so Ammnia can donate electron density better the the ion, then?

Well, at least i'm learning!
Original post by JMaydom
Clues coming up!!!

It's to do with how well the ligand can donate electron density to the metal ion.


Uff... what a question, but I give it a try: ammonia has a larger co-ordination number than water. That is why the electron configuration of ammonia is higher than the electron configuration of water, that is to say ammonia accepts more (pairs of) electrons at the central ion than water. Thus it donates more (pairs of) electrons from the central ammonia ion to the central metal ion, if they reacts with each other. So ammonia is better to form a bond. Its just an assumption. I'm not sure.
Original post by MusicNerd
so Ammnia can donate electron density better the the ion, then?

Well, at least i'm learning!


Yup, hence it forms stronger...... (not better.... what is objectively better about a bond..... be specific! that's directed to the OP)

Original post by Kallisto
Uff... what a question, but I give it a try: ammonia has a larger co-ordination number than water. That is why the electron configuration of ammonia is higher than the electron configuration of water, that is to say ammonia accepts more (pairs of) electrons at the central ion than water. Thus it donates more (pairs of) electrons from the central ammonia ion to the central metal ion, if they reacts with each other. So ammonia is better to form a bond. Its just an assumption. I'm not sure.


ummm, you seem to very lost to me.....

NH3 is a better donor as the electrons in the lone pair are higher in energy than the lone pairs in water. This is because of the electronegativity difference, O being more electronegative than N.

For a more advanced answer..... because the electrons are higher in energy there is a better energy match between the ligand and metal orbitals involved in bonding for NH3, so the covalent bonds are stronger.
Reply 23
Original post by JMaydom
NH3 is a better donor as the electrons in the lone pair are higher in energy than the lone pairs in water. This is because of the electronegativity difference, O being more electronegative than N.

For a more advanced answer..... because the electrons are higher in energy there is a better energy match between the ligand and metal orbitals involved in bonding for NH3, so the covalent bonds are stronger.


Is this how we describe co-ordinating ligands? :tongue:
(edited 10 years ago)
Reply 24
Original post by Mr Snips
Is this how we describe co-ordinating ligands? :tongue:


Yes....
Reply 25
Original post by BJack
Yes....

Good practice to describe the ligand's binding strength rather than the formation of strong covalent bonds
Original post by JMaydom


(...) ummm, you seem to very lost to me.....

NH3 is a better donor as the electrons in the lone pair are higher in energy than the lone pairs in water. This is because of the electronegativity difference, O being more electronegative than N. (...)


I see. Nitrogen in ammonia has a higher electronegativity (3,04) than Oxygen (2,2) in Water. And that is why the difference in terms of electronegativity is higher by far, if ammonia reacts with a metal. From that reason ammonia forms a bound stronger than water.

Original post by JMaydom
(...)
ummm, you seem to very lost to me..... (...)


Your clue with ligands confused me. I didn't understand what the coherence between electronegativity and ligand is. Do I have
your explanation right that a higher energy of ions electrons caused a higher difference in electronegativity, thus the ligands of a certain reaction product (ammonia in this case) and the metal orbital have a stronger energy to each other to bond? So the ligands of ammonia (on which electrons exist) and the orbital of metal make a stronger covalent bond than the ligands of water?
(edited 10 years ago)
I would post if I knew answers but I'm post GCSE, and I didn't bother covering much chem in the summer :h: thought I'd relax :biggrin:

Did some crappy unit 1 though
Original post by Mr Snips
Is this how we describe co-ordinating ligands? :tongue:


They are covalent bonds, but ionic contributions play a role due to the charge difference. The dative bonds you use in A-level are just a very old fashioned way of depicting things.

Original post by Kallisto
I see. Nitrogen in ammonia has a higher electronegativity (3,04) than Oxygen (2,2) in Water. And that is why the difference in terms of electronegativity is higher by far, if ammonia reacts with a metal. From that reason ammonia forms a bound stronger than water.

Read what I wrote again, you've written an answer which is almost the complete opposite of what I said

Your clue with ligands confused me. I didn't understand what the coherence between electronegativity and ligand is. Do I have
your explanation right that a higher energy of ions electrons caused a higher difference in electronegativity, thus the ligands of a certain reaction product (ammonia in this case) and the metal orbital have a stronger energy to each other to bond? So the ligands of ammonia (on which electrons exist) and the orbital of metal make a stronger covalent bond than the ligands of water?
The question was answered, right? but I can't see a new one. Who should ask a new question? The game must go on! it's very interesting and instructive.
Original post by Kallisto
The question was answered, right? but I can't see a new one. Who should ask a new question? The game must go on! it's very interesting and instructive.


What happens to the Infrared spectra of Hydrogen when it is substituted by Deuterium?.
Reply 31
Original post by Technetium
What happens to the Infrared spectra of Hydrogen when it is substituted by Deuterium?.


How in depth would you like to be? :tongue:
In short: The extra mass reduces the frequency of vibration of the bond. Beyond that I'd most likely have to look up a couple of equations to answer properly :redface:
Original post by joostan
How in depth would you like to be? :tongue:
In short: The extra mass reduces the frequency of vibration of the bond. Beyond that I'd most likely have to look up a couple of equations to answer properly :redface:


Expand on this point please, there is another reason. :smile:
Reply 33
Original post by Technetium
Expand on this point please, there is another reason. :smile:


Gulp.
Erm: After a quick google search, it appears that:
There is a disappearance of the C-H stretching (3020 cm-1) and bending (1220 cm-1) as well as the shift to lower frequencies in deuterated compounds.
Original post by joostan
Gulp.
Erm: After a quick google search, it appears that:
There is a disappearance of the C-H stretching (3020 cm-1) and bending (1220 cm-1) as well as the shift to lower frequencies in deuterated compounds.


I was looking for a comparison between their bond lengths.

Since Deuterium bonds are shorter they require more energy to break. This leads to a decrease in the wave-number of the X-H stretch (which you stated).

EDIT: You get the point though.
(edited 10 years ago)
Reply 35
Original post by Technetium
I was looking for a comparison between their bond lengths.

Since Deuterium bonds are shorter they require more energy to break. This leads to a decrease in the wave-number of the X-H stretch (which you stated).

Hmm, I didn't know that. Interesting. . .
I simply used the comparison to springs for my first deduction :redface:
Question: Derive an expression for pH at the Half-neutralisation point of a titration.
Original post by Technetium
I was looking for a comparison between their bond lengths.

Since Deuterium bonds are shorter they require more energy to break. This leads to a decrease in the wave-number of the X-H stretch (which you stated).

EDIT: You get the point though.


You've got to at least give a thorough answer if you're going to run this quiz.
Original post by joostan
Hmm, I didn't know that. Interesting. . .
I simply used the comparison to springs for my first deduction :redface:


Don't worry, it's a sort of half right, half wrong answer.....
Reply 39
Original post by JMaydom
You've got to at least give a thorough answer if you're going to run this quiz.



At least she is contributing questions to the thread!

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