Introductionairy(!) chemistry problem, SO4

  • Thread starter Fishingaxe
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Homework Statement


Ok, I recently started studying again after a 1.5 year break to pursue other things. I am trying to plow through this chemistry course, and I remember this forum where I basically got through my entire physics course because of the help of this forum which I greatly appreciate.

Ok, this is very simple but I have a hard time understanding this. Why does sulphate have 4 oxygens and -2 charge. I have a series of questions in my course, and among it, it said to write the formula for Aluminium chloride for example, which I understand is AlCl3 since Al has +3 charge and Cl has -1 so there has to be 3 of Cl to even things out, right? But this problem with writing sodium sulphate has me confused. I see that Sulfur and Oxygen is combined to make sulphur, but why on earth does it have to be 4 oxygens and 1 Sulfur? In my mind both needs 2e- to be happy, so why can't they just share it? If one atom of Sulfur shares with 1 atom of Oxygen, wouldn't they be happy? They could share one electron each and be content?

Do I just have to learn in my head that sulphate has the formula So42-? Likewise nitrate has NO3?

I am sorry, I am just massively confused by this.

Regards

Sonny

PS: If this is not worthy to be a thread I apologize, and if it is in the wrong place, please remove.
 

Answers and Replies

  • #2
SteamKing
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Homework Statement


Ok, I recently started studying again after a 1.5 year break to pursue other things. I am trying to plow through this chemistry course, and I remember this forum where I basically got through my entire physics course because of the help of this forum which I greatly appreciate.

Ok, this is very simple but I have a hard time understanding this. Why does sulphate have 4 oxygens and -2 charge. I have a series of questions in my course, and among it, it said to write the formula for Aluminium chloride for example, which I understand is AlCl3 since Al has +3 charge and Cl has -1 so there has to be 3 of Cl to even things out, right? But this problem with writing sodium sulphate has me confused. I see that Sulfur and Oxygen is combined to make sulphur, but why on earth does it have to be 4 oxygens and 1 Sulfur? In my mind both needs 2e- to be happy, so why can't they just share it? If one atom of Sulfur shares with 1 atom of Oxygen, wouldn't they be happy? They could share one electron each and be content?

Do I just have to learn in my head that sulphate has the formula So42-? Likewise nitrate has NO3?

I am sorry, I am just massively confused by this.

Regards

Sonny

PS: If this is not worthy to be a thread I apologize, and if it is in the wrong place, please remove.
Certain elements, like sulfur and nitrogen, have multiple valence states. With sulfur, you can have one sulfur atom oxidized to SO2, SO3, or SO4, depending on certain conditions:

https://en.wikipedia.org/wiki/Sulfur

Similarly, nitrogen can oxidize to more than a dozen different compounds:

https://en.wikipedia.org/wiki/Nitrogen_oxide

Elements like the alkali metals or the halogens generally have only one valence state. Their chemistry is much simpler to master.
 
  • #3
Borek
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Do I just have to learn in my head that sulphate has the formula So42-? Likewise nitrate has NO3?
At the beginning just remembering these formulas is the simplest approach. Later it is still the simplest approach - even once you can explain why the formula is SO42- it is easier to remember it, than to "derive" the correct formula from the first principles.

And beware - not NO3, but NO3-. These charges are pretty important here.
 
  • #4
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Thank you Steamking, and Borek for your responses. I will take your advice Borek and just remember the formulas for sulphate and nitrate, and thank you for the correction of the charge. I forgot to put it in.

It's fun to see you again Borek, if I remember correctly you helped me 2 years ago also, it is good to see this forum still thriving.
 

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