Explain the trend in melting points of Period 3 oxides from Na2O to Al2O3.

The melting points of Period 3 oxides increase from Na2O to Al2O3 due to the increasing strength of ionic bonds as the charge on the cation increases. Na2O has a melting point of 1130 °C, while Al2O3 has a much higher melting point of 2072 °C because of the stronger ionic lattice formed by Al3+ ions compared to Na+ ions. This answer is anchored to Period 3 oxides (A-level only).

The melting points of Period 3 oxides increase from Na2O to Al2O3 due to the increasing strength of ionic bonds as the charge on the cation increases. Na2O has a melting point of 1130 °C, while Al2O3 has a much higher melting point of 2072 °C because of the stronger ionic lattice formed by Al3+ ions compared to Na+ ions. is the best answer because it directly supports the AQA A-Level Chemistry objective to explain melting point trends of Period 3 oxides. This reasoning is anchored to Period 3 oxides (A-level only) in Properties of Period 3 elements and their oxides (A-level only), and it separates Period 3 oxide from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.