njl
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How come amines only form salts with the H+ cation?
Title, really. Ammonium chloride is formed when Ammonia is protonated by the acidic hydrogen from Hydrogen Chloride. In aqueous solutions this can be
represented as H+ protonating NH3 to for NH4+, with the positive charge balanced by a negative Cl- ion in solution. But why can't a compound like
Lithium chloride act in the same way (forming NH3Li+ and Cl-)? Is it because Lithium is bulkier than Hydrogen?
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outer_limits
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Hydrogen cation needs only 2 electrons to fill its 1s orbital and it exist in solution as H3O+ ions. When something undergoes a protonation it uses
it's own free pair of electrons to grab the hydrogen from hydronium ion.
Lithium as cation has already its 1s orbital filled. In order to create a stable compound you would have to fill 2s and 2p which will require to add 8
electrons.
[Edited on 6-8-2020 by outer_limits]
[Edited on 6-8-2020 by outer_limits]
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DraconicAcid
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You can also form a salt by reacting ammonia with CH3Br. NH3 + CH3Br --> NH3CH3(+) Br(-)
Also, Cu(2+) + 4 NH3 --> [Cu(NH3)4](2+)
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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clearly_not_atara
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Ammonium is not a "salt" or traditionally understood metal complex. It is a covalently bonded molecular ion. Lithium forms much weaker covalent bonds
with nitrogen because the difference in electronegativity is much larger. Thus the preferred configuration is Li(NH3)6+ which is made possible by much
longer-range monopole-dipole interactions.
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