Fill in the table with the bonding type and structural type shown by some Period 3 oxides.
Explain why the boiling point of $\text{SiO}_2$ is much higher than that of $\text{SO}_3$.
$\text{Al}_2\text{O}_3$ is an amphoteric oxide. Explain what is meant by amphoteric. Use chemical equations to support your answer.
State what you would observe when a small amount of $\text{Na}_2\text{O}$ is added to water.
Selenium reacts with fluorine to form $\text{SeF}_6$ molecules. Predict the shape of a $\text{SeF}_6$ molecule.
The most stable oxide of selenium is $\text{SeO}_2$. Gaseous $\text{SeO}_2$ changes to form a solid polymer, as shown. In the reaction, one $\text{Se}=\text{O}$ is replaced by two $\text{Se}-\text{O}$ to make a polymer. The bond enthalpy of $\text{Se}=\text{O}$ is $514\,\text{kJ mol}^{-1}$. Use these data to work out the bond enthalpy, in $\text{kJ mol}^{-1}$, of $\text{Se}-\text{O}$. ($\Delta H = -346\,\text{kJ mol}^{-1}$)
$\text{SeO}_2$ shows chemical reactions similar to $\text{SO}_2$. Suggest an equation to show how $\text{SeO}_2$ reacts with aqueous sodium hydroxide, $\text{NaOH}$.