Is Al No3 3 covalent or ionic

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alex_sch
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Posted: Jun 28, 2011 05:37 AM Title: Structural formula aluminum nitrate, Al (NO3) 3

My question:
Hello,

unfortunately i am not very fit when it comes to chemistry.
now i came across Al (NO3) 3 in my chemistry script and was wondering what the structural formula looks like.

At the beginning, I tried to set up a Lewis structural formula until I finally figured out that it was an ionic bond ...



My ideas:
how do you write down the correct formula in this case?

I find [Al3 +] [NO3-] 3 a little little (to show the structure on paper) ..

there is some model for ionic bonds that illustrates this better (such as the VSEPR model for covalent bonds).

Or does it have to be enough in this case that I imagine it as an ionic solid in the form of NaCl?

I hope I haven't written too much nonsense

Thanks in advance!
Chemistry guest
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Posted: Jun 28, 2011 1:29 PM Title: RE: Aluminum nitrate

Good day!
I would not be aware of any such representation. If you don't want to draw a unit cell, I would actually write Al3 + and show the nitrate ion as a multi-center bond (or with the mesomeric limit states).
magician4
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Registration date: 05.10.2009
Posts: 11677
Place of residence: Hamburg
Posted: Jun 28, 2011 4:55 PM Subject:

in addition:

where, if you go deeper into wanting to really draw something close to reality, you run the risk of falling into the approaching madness (at least if you want to grasp that based on the school chemistry level).

Due to the high formal charge on the aluminum atom, aluminum nitrate is a compound with a high covalent character. Similar to aluminum trichloride, there is an electron sextet on aluminum, which explains its considerable Lewis acidic characteristic.
It is therefore to be expected that, as in the chloride, some of the nitrate anions form bridges:

2 "AlCl3"= Al2Cl6

(Cl)2-Al- (2Cl) -Al- (Cl)2
(nice to look at: here)

the nitrations in the middle are not doing well: chemically they almost tear apart ...
..which is then recognizable by the extremely low decomposition point of 150 ° C for aluminum nitrate, because it finally breaks down the nitrations in the bridge

greeting

ingo
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alex_sch
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Posted: Jun 29, 2011 6:40 PM Subject:

Many thanks for the answers and especially for the example with AlCl3!
Chemistry enthusiast
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Posted: Feb 17, 2012 3:42 PM Title: Re: RE: Aluminum nitrate

Chemie-Gast wrote the following:
[...] that nitrate ion is still represented as a multi-center bond [...]


In the case of the nitrate ion, is that a 4-center-2-electron bond with regard to the "smeared over the entire molecule" double bond?
magician4
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Registration date: 05.10.2009
Posts: 11677
Place of residence: Hamburg