Mg vs Cu Stability

[matth87]

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A question came up like this in one of the passage I was just working.

It said Cu is more stable because it had a full D shell and Mg is less stable even though it has a full S shell. But Cu has a open valence electron in its s shell which didn't make sense to me. I would assume it would be less stable.

Is this correct?

 

[G1SG2]

A question came up like this in one of the passage I was just working.

It said Cu is more stable because it had a full D shell and Mg is less stable even though it has a full S shell. But Cu has a open valence electron in its s shell which didn't make sense to me. I would assume it would be less stable.

Is this correct?

I think a filled d subshell is more stable than a filled s subshell. Remember, some transition metals deviate from their predicted electron configuration (i.e., we'd expect Cu to be [Ar] 4s^2^3d^9, but it's [Ar] 4s^1 3d^10)-to get that filled or partially filled d subshell stability-d subshells rule.

 

[Pulsar]

A question came up like this in one of the passage I was just working.

It said Cu is more stable because it had a full D shell and Mg is less stable even though it has a full S shell. But Cu has a open valence electron in its s shell which didn't make sense to me. I would assume it would be less stable.

Is this correct?

You would expect copper's configuration to be [Ar]4s2 3d9, but it turns out it's more stable to take one of the electrons out of the s subshell and put it in the d subshell to make a half-filled s and completely filled d.