This question refers to the elements in the first three periods (H→Ar\text{H} \to \text{Ar}H→Ar) of the Periodic Table.
Select an element from the first three periods that fits each of the following descriptions.
(i) The element that forms a 2−2-2− ion with the same electron configuration as neon.
(ii) The element in Period 2 with the highest first ionisation energy.
(iii) The element in Period 3 which has the following successive ionisation energies:
(iv) The element in Period 3 which forms a compound with fluorine that has an octahedral molecular geometry.
(v) The element X\text{X}X in Period 3 which forms a hydride with the formula XH3\text{XH}_3XH3 having a molar mass of 34.0 g mol-1.
(vi) The diatomic gaseous element which has a density of 1.33 × 10-3 g cm-3 at room temperature and pressure (where one mole of gas occupies 24.0 dm3).
The table below shows some properties of selected Period 3 oxides.
| Group | 1 | 13 | 14 | 16 |
|---|---|---|---|---|
| Oxide | Na2O\text{Na}_2\text{O}Na2O | Al2O3\text{Al}_2\text{O}_3Al2O3 | SiO2\text{SiO}_2SiO2 | SO2\text{SO}_2SO2 |
| Melting point | High | High | High | Low |
| Electrical conductivity (liquid) | Good | Good | Poor | Poor |
Explain the properties shown in the table in terms of bonding and structure.
