Which of these species has a longer bond, $\mathrm{B}_2$ or $\mathrm{B}_2$ ? Explain in terms of molecular orbital theory.

In molecular orbital theory, what is a non bonding orbital?

Specify which hybrid orbitals are used by carbon atoms in these species: (a) $\mathrm{CO}$, (b) $\mathrm{CO}_2$, (c) $\mathrm{CN}^{-}$.

Specify which hybrid orbitals are used by carbon atoms in the following species: (a) CO, (b) $\mathrm{CO}_2$, (c) $\mathrm{CN}^{-}$.

Consider the simple model of an electric power system as shown in Figure The inductance, $L=0.25 \mathrm{H}$, represents the power line and transformer. The customer's load is $R_{\mathrm{L}}=100 \Omega$, and the customer adds $C=$ $25 \mu \mathrm{F}$ to increase the magnitude of $\mathbf{V}_0$. The source is $v_{\mathrm{s}}=1000$ $\cos 400 t \mathrm{~V}$, and it is desired that $\left|V_o\right|$ also be $1000 \mathrm{~V}$. (a) Find $\left|\mathrm{V}_0\right|$ for $R_{\mathrm{L}}=100 \Omega$. (b) When the customer leaves for the night, he turns off much of his load, making $R_{\mathrm{L}}=1 \mathrm{k} \Omega$, at which point, sparks and smoke begin to appear in the equipment still connected to the power line. The customer calls you in as a consultant. Why did the sparks appear when $R_{\mathrm{L}}=1 \mathrm{k} \Omega$ ?

Benzo[a]pyrene is a potent carcinogen found in coal and cigarette smoke. Determine the number of sigma and pi bonds in the molecule.

Write the ground-state electron configurations of the following transition metal ions: (a) $\mathrm{Sc^{3+}}$, (b) $\mathrm{Ti^{4+}}$, (c) $\mathrm{V^{5+}}$, (d) $\mathrm{Cr^{3+}}$, (e) $\mathrm{Mn^{2+}}$, (f) $\mathrm{Fe^{2+}}$, (g) $\mathrm{Fe^{3+}}$, (h) $\mathrm{Co^{2+}}$, (i) $\mathrm{Ni^{2+}}$, (j) $\mathrm{Cu^{+}}$, (k) $\mathrm{Cu^{2+}}$, (l) $\mathrm{Ag^{+}}$, (m) $\mathrm{Au^{+}}$, (n) $\mathrm{Au^{3+}}$, (o) $\mathrm{Pt^{2+}}$.

Write the ground-state electron configurations of the following transition metal ions: (a) $\mathrm{Sc}^{3+}$, (b) $\mathrm{Ti}^{4+}$, (c) $\mathrm{V}^{5+}$, (d) $\mathrm{Cr}^{3+}$, (e) $\mathrm{Mn}^{2+}$, (f) $\mathrm{Fe}^{2+}$, (g) $\mathrm{Fe}^{3+}$, (h) $\mathrm{Co}^{2+}$, (i) $\mathrm{Ni}^{2+}$, (j) $\mathrm{Cu}^{+}$, (k) $\mathrm{Cu}^{2+}$, (l) $\mathrm{Ag}^{+}$, (m) $\mathrm{Au}^{+}$, (n) $\mathrm{Au}^{3+}$, (o) $\mathrm{Pt}^{2+}$.

The electron configurations described in this chapter all refer to gaseous atoms in their ground states. An atom may absorb a quantum of energy and promote one of its electrons to a higher-energy orbital. When this happens, we say that the atom is in an excited state. The electron configurations of some excited atoms are given. Identify these atoms and write their ground-state configurations: (a) $1s^12s^1$
(b) $1s^22s^22p^23d^1$ (c) $1s^22s^22p^64s^1$ (d) $[\mathrm{Ar}]4s^13d^{10}4p^4$ (e) $[\mathrm{Ne}]3s^23p^43d^1$

The electron configurations described in Chapter 2 all refer to gaseous atoms in their ground states. An atom may absorb a quantum of energy and promote one of its electrons to a higher-energy orbital. When this happens, we say that the atom is in an excited state. The electron configurations of some excited atoms are given. Identify these atoms and write their ground-state configurations:
$1 s^2 2 s^2 2 p^2 3 d^1$.

Draw a molecular orbital energy level diagram for each of the following species: $\mathrm{He_2}$, $\mathrm{HHe}$, and $\mathrm{He_2^+}$. Compare their relative stabilities in terms of bond orders. (Treat HHe as a diatomic molecule with three electrons.)

The triiodide ion ($\mathrm{I^-_3}$ ) in which the I atoms are arranged along a straight line is stable, but the corresponding $\mathrm{F^-_3}$ ion does not exist. Explain.

Draw resonance structures for the following ions: $\mathrm{SO_3^{2-}}$.

Draw resonance structures for the following ions:
$\mathrm{HSO}_3^{-}$.