Question 5
In a dot-and-cross diagram, what is the difference between an electron drawn as a dot and one drawn as a cross?
The right answer is the one marked above.
Electrons that came from different atoms. The two symbols record which atom supplied which electron, so a shared pair shows as one dot beside one cross.
Protons are never drawn in these diagrams. Bonding and lone pairs are told apart by position, not by symbol, and both kinds can be drawn as dots. Only valence electrons appear at all, so shells are not being distinguished.