One of the molecular orbitals of the H2− ion can be sketched as follows:
a. Is the molecular orbital a 𝜎 or 𝜋 MO? Is it bonding or antibonding?

The structure of borazine, B₃N₃H₆, is a six-membered ring of alternating B and N atoms. There is one H atom bonded to each B and to each N atom. The molecule is planar. (e) What are the hybridizations at the B and N atoms in the Lewis structures from parts (a) and (b)? Would you expect the molecule to be planar for both Lewis structures? Would you expect the molecule to be planar for both Lewis structures?

The highest occupied molecular orbital of a molecule is abbreviated as the HOMO. The lowest unoccupied molecular orbital in a molecule is called the LUMO. Experimentally, one can measure the difference in energy between the HOMO and LUMO by taking the electronic absorption (UV-visible) spectrum of the molecule. Peaks in the electronic absorption spectrum can be labeled as π_2p-π_2p*, σ_s-σ_2s*, and so on, corresponding to electrons being promoted from one orbital to another. The HOMO-LUMO transition corresponds to molecules going from their ground state to their first excited state. (c) The electronic absorption spectrum of the N₂ molecule has the lowest energy peak at 170 nm. To what orbital transition does this correspond?

The structure of borazine, B₃N₃H₆, is a six-membered ring of alternating B and N atoms. There is one H atom bonded to each B and to each N atom. The molecule is planar. (a) Write a Lewis structure for borazine in which the formal charge on every atom is zero.

Azo dyes are organic dyes that are used for many applications, such as the coloring of fabrics. Many azo dyes are derivatives of the organic substance azobenzene, C12H10N2. A closely related substance is hydrazobenzene, C12H12N2. The Lewis structures of these two substances are

(Recall the shorthand notation used for benzene.) (b) How many unhybridized atomic orbitals are there on the N and the C atoms in each of the substances? How many unhybridized atomic orbitals are there on the N and the C atoms in hydrazobenzene?

One of the molecular orbitals of the H2− ion can be sketched as follows:

d. Compared to the H—H bond in H2, the H—H bond in H2− is expected to be which of the following?

i. shorter and stronger

ii. longer and stronger

iii. shorter and weaker

iv. longer and weaker or

v. the same length and strength

Place the following molecules and ions in order from smallest to largest bond order: H2+,B2,N2+,F2+, and Ne2.