Energy Diagram for Cyclobutadiene ·Following Hund's rule,two electrons are in separate nonbonding 不3 orbitals. line ·This diradical would be very reactive. TI- Copyright2005 Pearson Prentice Hall,Inc => Chapter 16 12 Chapter 16 12 Energy Diagram for Cyclobutadiene • Following Hund’s rule, two electrons are in separate orbitals. • This diradical would be very reactive. =>