Why is copper diamagnetic without a prefix?

[schrodingerscat11]

Homework Statement

Our teacher said that if a material has an odd number of electrons, it implies a paramagnetic behavior. Copper, according to him, has odd number of electrons but is considered a diamagnetic material. He asks us to explain this phenomenon.

Homework Equations

Copper has 29 electrons. And its electron configuration is 1s²2s²2p⁶3s²3p⁶4s¹3d¹⁰

The Attempt at a Solution

According to what they (internet) say, the d subshell borrowed an electron from the s subshell on n=3 (see electron configuration). This accounts for the diamagnetism. But isn't it that the electron on the s subshell is unpaired, and should cause the Cu to paramagnetic? Or is it the outermost subshell that is only considered? :( Thanks a lot.

 

[TeethWhitener]

This is the received wisdom for bulk metallic copper, namely that the paramagnetic contribution from the unpaired 4s electron is smaller than the diamagnetic contribution from the closed 3d subshell. So both effects exist, but the diamagnetism is stronger.