[T]

Hello,

I am confused by the polyatomic ion sulfate. Firstly since it has a charge of 2- that means it has 2 extra electrons, does it get the electrons from a metal when sulfur and oxygen react with the metal?

Also in the lewis dot diagram, sulfur has more than 8 electrons in it's outer shell. I don't understand why sulfur can have more than 8 electrons in it's outer shell because of the octet rule, I have searched google for it and I don't really understand their definitions. Is it because it is a central atom it doesn't need to follow the octet rule? Or is it because sulfur has a special electron configuration that allows this. Sulfur's electron configuration is 1s², 2s², 2p⁶, 3s², 3p⁶ but I am not sure where the other 2 electrons go, can someone explain this since the next subshell would be subshell 4s and it seems unlikely that another shell (energy level) would be filled, or would it fill the d subshell, but then this would go against the subshell order. Thanks

[Shipwreck]

Also in the lewis dot diagram, sulfur has more than 8 electrons in it's outer shell.

No it doesn't. Please elaborate.

[T]

Ok:

[Shipwreck]

Ah, yes, Sorry. You're right. I didn't consider the other types of bonding structures.

http://chemwiki.ucdavis.edu/Theoretical_Chemistry/Chemical_Bonding/Lewis_Theory_of_Bonding/Violations_of_the_Octet_Rule

Check example 2 towards the bottom of the page.

[Enthalpy]

Atomic sulphur has the eelctronic configuration
1s²2s²2p⁶3s²3p⁴ (not 6)

[T]

What I meant was the electronic configuration of sulfur in SO₄^2-.

Thanks

[Corribus]

By rigorous formalism, sulfur in the sulfate ion has a +6 oxidation state. So, you should be able to determine its electron configuration accordingly.

However, it's not really helpful to think about it this way, since electrons are at least partially shared between atoms. Also, the octet rule isn't some hard and fast law of physics. And it doesn't really apply to many main group elements from the third row of the periodic table down. There are a lot of competing views as to why this is.

Answering your first question - sulfate always has a positive counter-ion, typically but not always one or more metal cations. (E.g., ammonium sulfate would be an example of the latter.) You can think of the extra electrons as having being taken from this counter-ion, forming a salt.

[T]

I see, if I mixed sulfur, oxygen and calcium together and heated the mixture will I get some calcium sulfate?

Thanks

[Corribus]

Possibly some; but you'd probably also get a lot of other stuff, calcium oxide, sulfur dioxide, calcium sulfide, etc. My guess is that having a hydrogen source - e.g., water - would help, as a precursor to sulfuric acid - particularly in the presence of some kind of metal catalyst.

[T]

I see, if I mix sulfur and oxygen will only sulfur dioxide be produced and not sulfate? Since there wont be electrons to achieve 2- for the sulfate.

Thanks