What type of covalent bond diagram only shows the outer shell of electrons?

Correct answer: Dot-and-cross-diagram

Dot-and-cross diagrams are used to represent covalent bonds. The shared electron from one atom is shown as a dot, while the shared electron from the other atom is shown as a cross.

When drawing dot-and-cross diagrams for covalent bonds, you only need to show the electrons in the highest occupied energy level, as only these are involved.