why is calcium listed as paramagnetic even though it has no unpaired electron ??





Now from electronic configuration its is seen that all electron are paired up i.e Ca should be diamagnetic. The magnetic factor not only depends on the electronic configuration but also depends on the vacant orbital that are present next to valence orbital. Now Ca contain an empty d orbital whose energy is very close to valence s orbital. This presence of low lying vacant orbital near electrons of  4s orbital sometime cause transition of electron of 4s and introduce the paramagnetic character by creating an unpaired electron in s orbital and vacant d orbital. This process occur due to less energy difference outer s and d orbital.

Secondly, due to above process their occur delocalization of electron as electron tends to go to d orbital and come back to s orbital again and again . This allow Ca to have some amount of net paramagnetic character.
But mostly Ca in its ground state is diamagnetic.

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Metallic systems are a whole different ballgame. Because the electrons are delocalized, we don't have this picture of isolated atoms with little electron spins attached. The electrons are no longer trapped together in an atom, leading to net spin. Instead we have extended electrons with equal number spin up and spin down, and when we apply a magnetic field we get Pauli-paramagnetism. This is quite weak in a good metal and it competes with the also weak diamagnetism of the core electrons and such. The diamagnetism can dominate: gold and zinc are diamagnetic. Calcium by the way is metallic even though the s shell is full - the s and p bands mix and cross so that their is a Fermi surface....

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After seeing this question i am also ..searching about it hope the above paragraph helps. :-)

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Metallic systems are a whole different ballgame. Because the electrons are delocalized, we don't have this picture of isolated atoms with little electron spins attached. The electrons are no longer trapped together in an atom, leading to net spin. Instead we have extended electrons with equal number spin up and spin down, and when we apply a magnetic field we get Pauli-paramagnetism. This is quite weak in a good metal and it competes with the also weak diamagnetism of the core electrons and such. The diamagnetism can dominate: gold and zinc are diamagnetic. Calcium by the way is metallic even though the s shell is full - the s and p bands mix and cross so that their is a Fermi surface....

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After seeing this question i am also ..searching about it hope the above paragraph helps. :-)

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