Sciencemadness Discussion Board - Come on? Silver 1 or 4 or 11 valence....

Come on? Silver 1 or 4 or 11 valence....

CHRIS25 - 10-5-2014 at 08:41

it depends on who you ask, and I can list the references if you like. This is bloody confusing. I am trying to understand the transition metals to know exactly how many valence electrons they have (my particular interest right now is Silver because I want to do a reaction); I was trying to do the ionic equation for Ag + HNO₃ listing the oxidation numbers, drawing the lewis dots and even, yes even building the models on my desk with those children's red white and grey molecule building thingys. I came unstucjk at what I thought was the simplest thing in the universe to work out when I could not work out the valence electrons in Silver.

Texium - 10-5-2014 at 09:09

Silver only exists in compounds as 1+ except in very rare cases.

[Edited on 5-10-2014 by zts16]

blogfast25 - 10-5-2014 at 09:21

Nitric acid is different from other strong acids in the sense that the nitrate ion in acidic conditions is also an oxidiser:

HNO3(l) + H2O === > H3O+ + NO3(-) (dissociation of nitric acid in water)

The H3O+ is an oxidiser in the way we discussed.

But the nitrate is an oxidiser too, and gets reduced to NO:

NO3- === > NO

Add two H2O on the right, to balance in O:

NO3- === > NO + 2 H2O

Add H+ to the left to balance in H:

NO3- + 4 H+ === > NO + 2 H2O

Now add 3 e to make it neutral:

NO3- + 4 H+ + 3 e- === > NO + 2 H2O

In air, the NO immediately reoxidises to NO2, hence the brown fumes when you dissolve metals in nitric acid.

Metals like silver and copper cannot be oxidised by H3O+ alone, hence the use of nitric acid. They won't dissolve in H2SO4 or HCl (copper does dissolve in conc. H2SO4 but that's another story).

+1 is Ag's main oxidation state but it can be pushed to +2 in extreme conditions.

[Edited on 10-5-2014 by blogfast25]

CHRIS25 - 10-5-2014 at 09:23

Quote: Originally posted by zts16

Silver only exists in compounds as 1+ except in very rare cases.

[Edited on 5-10-2014 by zts16]

Yes I was originally at 1 valence electron but then I looked here:http://www.ptable.com/#Property/Valence and it clearly states 4. Then that caused me to research further and I came across this: https://uk.answers.yahoo.com/question/index?qid=200803271358...
Which I ignored for obvious reasons apart from noticing 11 valence, so I searched further and further and I kept seeing 4 and then 1 again.
Then I had a nervous breakdown.

So I will stick with 1 seeing that 1 is actually in its outer shell, why 4 though?

@Blogfast exactly what I was doing just as I read your post, but your explanation just confirms taht at least on this area I am getting things more right now. It was just this valence thing.

[Edited on 10-5-2014 by CHRIS25]

[Edited on 10-5-2014 by CHRIS25]

blogfast25 - 10-5-2014 at 09:27

Quote: Originally posted by CHRIS25

Quote: Originally posted by zts16

Silver only exists in compounds as 1+ except in very rare cases.

[Edited on 5-10-2014 by zts16]

Yes I was originally at 1 valence electron but then I looked here: and it clearly states 4. Then that caused me to research further and I came across this: https://uk.answers.yahoo.com/question/index?qid=200803271358...
Which I ignored for obvious reasons apart from noticing 11 valence, so I searched further and further and I kept seeing 4 and then 1 again.
Then I had a nervous breakdown.

So I will stick with 1 seeing that 1 is actually in its outer shell, why 4 though?

[Kr] 4d10 5s1 is the electron configuration of Ag. The 5s1 is the lone valence electron.

CHRIS25 - 10-5-2014 at 09:38

sorry blogfast now you've lost me, I have not even dared to touch on orbitals yet - could you though confirm for, me since we know that NO is oxidized immediately on liberation from water but NO2 is Not produced in solution, that the stoichiometrically correct amount in solution should be based on A) since this is what is produced 'in' solution, i have seen B) tauted about but I disagree (at the moment). I am not being finiglety or pedantic, i am just trying to exact more precision in my chemistry than I did many months ago.

A) 3 Ag + 4 HNO3 = 3 AgNO3 + 2 H2O + NO

B) Ag + 2 HNO3 = AgNO3 + H2O + NO2

BromicAcid - 10-5-2014 at 09:45

Valence 4 does not exist as far as I have seen. The main silver compound that had been assigned a formal +4 oxidation state, AgO2 was later found via x-ray crystalography and other techniques to actually be a mix of +3 and +1 oxidation states and is listed correctly on the wiki article as Silver (I,III) Oxide.

You can see +2 in some common compounds like AgF2.

[Edited on 5/10/2014 by BromicAcid]

blogfast25 - 10-5-2014 at 09:53

Chris:

A) is correct.

The NO then oxidises to NO2 but that is a separate event.

[Edited on 10-5-2014 by blogfast25]

CHRIS25 - 10-5-2014 at 09:57

Ok Bromic, but what is confusing me is that if you hover over all the transition metals on this table, the valence electron listed is hardly ever in agreement with what I am reading 'logically' as the outer shell valence listed. After all it is what is on the outer shell that is valence. If it's not then I will abandon chemistry and take up embroidery!

[Edited on 10-5-2014 by CHRIS25]

blogfast25 - 10-5-2014 at 10:05

Which table are you referring to? The periodic table or a specific periodic table you found on Tinternets?

Texium - 10-5-2014 at 10:06

Yes, the outermost energy level, 5, has 1 electron, because silver prefers to store the electron that would be in 5s² in 4d¹⁰ so that the 4th energy level is full. Because of that, it has only 5s¹

CHRIS25 - 10-5-2014 at 10:11

Quote: Originally posted by blogfast25

Which table are you referring to? The periodic table or a specific periodic table you found on Tinternets?

this one http://www.ptable.com/#Property/Valence

blogfast25 - 10-5-2014 at 10:21

Chris:

That table contains some errors and some over-simplifications: for Fe it gives +6 but that is only the HIGHEST one and the least stable at that.

With the transition elements (D-block elements) often some or all of the d orbital electrons are also 'available'. For instance for Ti we have [Ar] 3d2 4s2, which would suggest valence 2. But the 3d2 electron are energetically speaking sufficiently close to the 4s ones to be able to act as valence electrons also. So Ti's main oxidation state is +4. This is true of the other elements of that group.

These atoms don't really care about the somewhat simplistic 'rules' we imagine: if it leads to a stable state it will happen, no matter how much of an aberration it may look like to us.

[Edited on 10-5-2014 by blogfast25]

CHRIS25 - 10-5-2014 at 10:28

Ok Blogfast I guess I will have to find a decent table now. I aqm still getting confused over redox. I had to pick a complex one! The silver is oxidized by the nitrate ion, the hydrogen atom has of course dissociated I understand all this. But where there is Oxidation there must be reduction. Now when I balance the Nitric acid charge on the left with the nitrate charge from silver nitrate on the right I see no change Except that the silver has lost one electron and is now more positively charged. If the nitrate has oxidized silver, where is the reducing agent? and what the hell has been reduced?

[Edited on 10-5-2014 by CHRIS25]

CHRIS25 - 10-5-2014 at 10:40

Quote: Originally posted by blogfast25

Chris:

A) is correct.

The NO then oxidises to NO2 but that is a separate event.

[Edited on 10-5-2014 by blogfast25]

I missed this post - so I did pick a complicated one - I just threw my plastic silver nitrate model across the room....I still can't see any changes, I would expect to find something that has Gained electrons and is now more negatively charged - is it hiding?

[Edited on 10-5-2014 by CHRIS25]
Ok it is hiding, no wonder I could not see it, it was in the NO3, so the N in NO3 has absolutely no charge because it is in a polyatomic configuration; but when liberated as NO it now has a +2 charge - HAVE I GOT IT NOW....please.....

[Edited on 10-5-2014 by CHRIS25]

blogfast25 - 10-5-2014 at 10:52

Chris:

The Ag has lost an electron, so it has been oxidised.

Work out the oxidation numbers for N in the nitrate and in the NO. In nitrate the oxidation number of N is +5. In NO it is +2. There's your reduction: it's the nitrogen in one of the nitrate ions that has absorbed (very simply put!) the electrons from the silver. Note that three nitrate ions are spectators: you find them both on the left and on the right, unchanged.

CHRIS25 - 10-5-2014 at 11:01

Quote: Originally posted by blogfast25

Chris:

The Ag has lost an electron, so it has been oxidised.

Work out the oxidation numbers for N in the nitrate and in the NO. In nitrate the oxidation number of N is +5. In NO it is +2. There's your reduction: it's the nitrogen in one of the nitrate ions that has absorbed (very simply put!) the electrons from the silver. Note that three nitrate ions are spectators: you find them both on the left and on the right, unchanged.

Relief at last - I am getting it - slowly with bumps and bruises. Thankyou Blogfast.

Magpie - 10-5-2014 at 12:58

Quote: Originally posted by blogfast25

Chris:

The Ag has lost an electron, so it has been oxidised.

Therefore Ag is the reducing agent.

CHRIS25 - 10-5-2014 at 13:36

Quote: Originally posted by Magpie

Quote: Originally posted by blogfast25

Chris:

The Ag has lost an electron, so it has been oxidised.

Therefore Ag is the reducing agent.

Yes, thanks Magpie, now I understand, and nitrate is the Oxidizer, which by its very nature is a powerful oxidizer anyway, but the complexity for me was suddenly realizing that HNO3 is polyatomic and I overlooked the N after the H had dissociated into the water.

macckone - 11-5-2014 at 06:57

Recent research on NaCl shows that at extreme pressure,
the valence categorization as we know it breaks down.

http://www.sciencedaily.com/releases/2013/12/131219142313.ht...

Valence rules are rules of general applicability and apply in
most cases. For silver the rule is +1. That doesn't mean that
other valences can't or don't exist. Nor can the compounds
we use at STP be expected to exist in the same form at
extreme pressures. And there is evidence that on a universal
scale compounds exist at either extreme pressure or absolute
vacuum with very little at what we consider STP.

CHRIS25 - 11-5-2014 at 07:17

Hi very interesting article, and it reminds about some laws of physics being turned upside down in cryogenic chambers.