Chapter 11, Problem 41QP

The melting points of the oxides of the third-period elements are given in parentheses: ${\text{Na}}_{\text{2}}{\text{O (1275°C), MgO (2800°C), Al}}_{\text{2}}{\text{O}}_{\text{3}}\left(\text{2045°C}\right){\text{, SiO}}_{\text{2}}{\text{(1610°C), P}}_{\text{4}}{\text{O}}_{\text{10}}\text{(580°C)}{\text{. SO}}_{\text{3}}\text{(16}\text{.8°C),}$ $C{l}_2{O}_7(-91.5°C).$ Classify these solids in terms of crystal types.