Why is hydrated copper (II) ion a complex but hydrated sodium ion isn't?

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CaptainJackFail
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Question : The hydrated copper(II) ion is classed as a complex but the hydrated sodium ion is not.
By considering the interaction between the water molecules and the sodium ion, explain why the hydrated sodium ion is not considered to be a complex.

Mark Scheme:
Oxygen atoms in water molecules have δ− charge. (1)
Which form electrostatic / ion-dipole attractions with sodium (ion). (1)
ALLOW for one mark copper(II) ions form dative covalent bonds but sodium ions do not (both needed)

I don't know about you, but I'm also certain that copper is also positively charged, just like sodium! so wouldn't oxygen and copper also form dipole-dipole attraction? This is confusing.
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Gerry-Atricks
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Sodium is not a transition metal
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JustARandomer123
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Copper is a transition metal so it forms dative bonds with water ligands which in turn forms a complex ion. Sodium isn't a transition metal, so it's not able to do this
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Dynamic_Vicz
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I think it has something to do with the valent electrons of the two metals. The valent electrons of the transitional metals are in the d sub shell whereas the valent electrons of the alkali metals are in the s sub shell.

When the metals are in their ionic state they lose electrons differently depending on the energy levels.

It looks like the answer may simply just be that sodium isn't a transitional metal.
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CaptainJackFail
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(Original post by glad-he-ate-her)
Sodium is not a transition metal
(Original post by JustARandomer123)
Copper is a transition metal so it forms dative bonds with water ligands which in turn forms a complex ion. Sodium isn't a transition metal, so it's not able to do this
I should probably type out the question as well, apologies:

Question : The hydrated copper(II) ion is classed as a complex but the hydrated sodium ion is not.
By considering the interaction between the water molecules and the sodium ion, explain why the hydrated sodium ion is not considered to be a complex.

Mark Scheme:
Oxygen atoms in water molecules have δ− charge. (1)
Which form electrostatic / ion-dipole attractions with sodium (ion). (1)
ALLOW for one mark copper(II) ions form dative covalent bonds but sodium ions do not (both needed)

Your guys' answers are correct but would only gain one mark out of two. wouldn't the interaction between water molecules and the COPPER ion also be dipole - dipole? since Cu is +ve and O is -ve?
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Gerry-Atricks
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(Original post by CaptainJackFail)
I should probably type out the question as well, apologies:

The hydrated copper(II) ion is classed as a complex but the hydrated sodium ion is not.
By considering the interaction between the water molecules and the sodium ion, explain why the hydrated sodium ion is not considered to be a complex.

Your guys' answers are correct but would only gain one mark out of two. wouldn't the interaction between water molecules and the COPPER ion also be dipole - dipole? since Cu is +ve and O is -ve?
bonding between sodium and water is partially ionic( due to dipoles) but between copper and water is dative covalent as the lone pair on oxygen is donated to central metal
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JustARandomer123
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Copper ions don't form dipole interactions with water; in place of that, dative bonds are formed. It works differently with transition metals
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