Question

What is the number of unpaired electrons for the following compounds:
Cobalt (II) chloride
Copper (II) chloride
Iron (II) chloride
Manganese (II) chloride
Nickel (II) chloride
Zinc chloride
I don't know how to do this

Answer 1

Co is 1s2 2s2 2p6 3s2 3p6 3d7 4s2
Co^2+ is 1s2 2s2 2p6 3s2 3p6 3d7
For the d orbitals draw 5 boxes. I can't do this on this forum but 5 boxes in a line (row). The boxes look like this for Fe and Fe^3+.
https://www.google.com/search?q=Co+orbital+boxes&tbm=isch&tbo=u&source=univ&sa=X&ei=cSCvVKezJ876ggTBm4LIAw&ved=0CDwQsAQ&biw=1024&bih=609
For Co just put an electron in the first box, another in the next box, and third in the third box, and continue until all five boxes have at least one electron in each. Then you start pairing the electrons. The next (the sixth electron) must go into the first box that already has one electron in it, the 7th electron must go in the second box with one already there. That leaves the last three boxes with only 1 electron in each so there are three unpaired electrons. All of them are done this way.