# Homework 19 (Due 5/25/2016)


Name: ______________________________

Section: _____________________________

Student ID#:__________________________

## Q19.1

$$CO_2$$ is experimentally determined to be diamagnetic. If a student proposed the following structure to explain. Is a valid Lewis diagram? Does this Lewis diagram predict a diamagnetic species and if not, why?

## Q19.2

Does $$\ce{Br_2C=CHBr}$$ have a dipole moment?

## Q19.3

What is the value of $$\psi^2_g$$ (The probability density of finding the electron) at either nucleus in $$Li^+_2$$ using the below equation for $$\psi_g$$ ? What is the value of $$\psi^2_g$$ at the midpoint of the bond? Use $$R_e =106\; pm$$ and $$S = 0.86$$

$\psi_g = \dfrac{1}{\sqrt{2(1+S)}}(1s_a + 1s_b)$

The hydrogenic radial function of a 1s orbital is

$R_{1,0} (r) = 2 \left(\dfrac{Z}{a_o}\right)^{3/2} e^{-\frac{Zr}{a_o}}$

with the angular wave function (in this case $$Y_{0,0}$$)

$Y_{0,0} = \dfrac{1}{\sqrt{4\pi}}$

## Q19.4

The first excited states of $$H_2^-$$ are formed by exciting an electron from the antibonding $$1\sigma_u$$ molecular orbital to the bonding $$2\sigma_g$$ orbital. Write the electron configuration of the ground state and excited-state $$H_2^-$$ molecules. What is the bond order of $$H_2^-$$ in both states? Is $$H_2^-$$ diamagnetic or paramagentic in either state?

## Q19.5

Which two second row homonuclear diatomic molecules do not follow conventional Molecular Orbital energy levels of the other second row homonuclear diatomic? Which are they and what is the difference?

## Q19.6

A excited state of $$O_2^*$$ is formed by exciting a single electron in $$O_2$$ from the molecular orbital $$1\pi_g$$ to the orbital $$3\sigma_u$$. Note that $$^*$$ is used to represent an excited state species, not an antibonding molecular orbital.

1. Write the electron configuration.
2. What is the bond order of $$O_2^*$$?

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