9. Consider the cyclic cation C,H,*. a. How many electrons are in the n system? Circle your answer. [2 pts] 8 9 10 b. Use the appropriate polygon (below) to complete the Hückel analysis of this π system by drawing in the energy levels of the MOs and filling them with the number of electrons you answered in part a. Only one of the four polygons is correct for the analysis in both ring size and- orientation. [6 pts] 8 8 9 9 c. Is the cyclic cation C,H,* aromatic, antiaromatic, or nonaromatic? Circle your answer. [2 pts] aromatic antiaromatic nonaromatic

Calculate the bond order for an ion with this configuration (σ2s)2(σ∗2s)2(σ2px)2(π2py,π2pz)4(π∗2py,π∗2pz)3

44. The molecule H3* has long been speculated to exist. The interest here is that the addition of the smallest bit of nuclear matter, a proton, now introduces additional nuclear repulsion over the H₂ problem. The issue was whether electron distributions could lead to a stable configuration. a) Draw what you think would be the most stable structure for H3* and show all the Coulombic terms (write out the potential needed for the corresponding Schroedinger equation). b) Draw what you think is the least stable configure of the 3 protons and 2 electrons. c) It is found that the structure involves the rotation of one proton around the other two, and interchange of which proton is rotating. Offer a potential explanation (think tunneling).

For the O2, O2+, O2-,           Draw the molecular orbital electron configuration (1sσ2, 1sσ*2, 2sσ2,             2sσ*, 2pσ2, 2pπ2,,,, ) for O2-.

An energy level scheme for the orbitals of second row diatomic molecules O, through Ne2 , lists the molecular orbitals in the following order of increasing energy 02 < o'2s < Ozp(z) < T2p(y)- 7T2P(x) < T*2p(y), 7T* 2p(x) < o*2plz) Based on this energy level scheme, how many electrons are there in all of the antibonding molecular orbitals of the F2* ion in its ground state?

The MO of the ground state of a heteronuclear diatomic molecule AB is Vmol = CA4A + CB4B If a bonding electron spends 90% of its time in an orbital pA on atom A and 10% of its time in øB on atom B, what are the values of CA and Cg? (Neglect the overlap of the two orbitals.)

Write the MO configurations for tje valence electrons in C2 starting with ( σ2s)2.

6. For heteronuclear diatomic molecules, the energy-level diagrams of the molecular orbitals need to be modified via calculation. For both NO and CN', the order of molecular orbitals are similar to that of O,. Write electron configurations of NO and CN including core electrons, starting with o1,'01,*². Which bond is stronger? (hint: bond order)

Fill in the Molecular Orbital Energy Diagram for the diatomic molecule He2. E helium 2s- — 1s- A MO'S 0*25 02s 0*15 01s helium - — B 2s 1s

Draw the molecular orbital energy diagram (like we did in class, not the fancy general chemistry diagrams) for the bond between the nitrogen atom labeled a and the carbon atom labeled b in the following molecule. Clearly indicate which atomic orbitals are interacting, which resulting orbital the electrons are in, and label HOMO, LUMO, bonding and antibonding orbitals, and sigma (o), sigma* (o*), pi (n), and pi* (7*) where appropriate.