Transition Metals (Part 2)

Why is copper red? Why is it so soft compared to, say, nickel—the element right next to it in the periodic table? Why is it such a good conductor of electricity?

All of this stems from a violation of Hund’s rules. Let me explain.

In Part 1, I explained the basic math of transition metals. Now I just want to talk about how the first row of transition metals fill up the 10 orbitals in the 3d subshell, and what’s special about copper:

These elements have all the electrons that argon does: ...