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

Draw resonance structures for the following ions:
$\mathrm{PO}_4^{3-}$.

Hydrogen and methanol have both been proposed as altern atives to hydrocarbon fuels. Write balanced reactions for the complete combustion of hydrogen and methanol and use standard enthalpies of formation to calculate the amount of heat released per kilogram of the fuel. Which fuel contains the most energy in the least mass? How does the energy of these fuels compare to that of octane ($C_8H_{18}$)?

When 1 mol of a fuel burns at constant pressure, it produces 3452 kJ of heat and does 11 kJ of work. What are $\Delta E$ and $\Delta H$ for the combustion of the fuel?

Draw resonance structures for the following ions: $\mathrm{HSO^-_4}$.

Write a Lewis structure for the HCN molecule showing specifically how the octet rule is satisfied.

Draw three resonance structures for the $\mathrm{OCN^-}$ ion. Show formal charges.

What does the principal quantum number determine? Check all that apply.

a) the energy of an electron in the outer shell

b) the possible number of electrons in particular orbital

c) the orientation of the orbital

d) the shape of the orbital

e) the energy of an orbital

f) the overall size of an atom

g) the overall size of an orbital

What is a quantum-mechanical orbital?

Write three resonance structures for hydrazoic acid, $\mathrm{HN}_3$. The atomic arrangement is HNNN. Show formal charges.

Write Lewis structures for the following species, including all resonance forms, and show formal charges:
$\mathrm{CH}_2 \mathrm{NO}_2^{-}$
The relative positions of the atoms are as follows:

$$\begin{array}{lllll} \mathrm{O} & & \mathrm{H} & & \mathrm{O} \\ \mathrm{H} & \mathrm{C} & & \mathrm{CN} & \\ \mathrm{O} & & \mathrm{H} & & \mathrm{O} \end{array}$$

Write Lewis structures for the following species, including all resonance forms, and show formal charges:
$\mathrm{HCO}_2$
The relative positions of the atoms are as follows:

$$\begin{array}{lllll} \mathrm{O} & & \mathrm{H} & & \mathrm{O} \\ \mathrm{H} & \mathrm{C} & & \mathrm{CN} & \\ \mathrm{O} & & \mathrm{H} & & \mathrm{O} \end{array}$$

Write Lewis structures for the following molecules:
$\mathrm{COBr}_2$ ( $\mathrm{C}$ is bonded to $\mathrm{O}$ and $\mathrm{Br}$ atoms).

Write Lewis structures for the following molecules:
$\mathrm{HClO}_3$.