Gen Chem formula question (What do brackets signify?

[MikeMitchell]

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I see passages where a formula is written as;

Na[Al(OH)4]

Does this mean the Na is actually dissociated from the compound in solution? Is this why its not written as NaAlOH4? Why would they not write them seperately?

Thanks!

 

[justhanging]

I see passages where a formula is written as;

Na[Al(OH)4]

Does this mean the Na is actually dissociated from the compound in solution? Is this why its not written as NaAlOH4? Why would they not write them seperately?

Thanks!

It doesn't matter how they write it. Its a salt, they write it with brackets to make the cation and the anion parts more easy to see. Na will dissociate if the salt is soluble just like any other salt.

 

[Isoprop]

The brackets are there because what's inside the bracket is a coordination complex. The sodium forms an ionic bond to the complex and is probably soluable in water. Inside the complex, there are coordinate covalent bonds between the Al and the OH ligands.

 

[MikeMitchell]

The brackets are there because what's inside the bracket is a coordination complex. The sodium forms an ionic bond to the complex and is probably soluable in water. Inside the complex, there are coordinate covalent bonds between the Al and the OH ligands.

Coordination complex or metal complex, I wasn't aware of this term before. Excellent answer, thanks!