Question

Discuss the important characteristics of group 16 elements.

Answer 1

1. Atomic and ionic radii increase down the group but are smaller than Group 15 elements.
2. Density, melting and boiling points increase down the group.
3. High ionisation energies, but decrease down the group; lighter elements show lower first ionisation energy than Group 15 analogues.
4. High electronegativity, with oxygen being the second most electronegative element; electronegativity decreases down the group.
5. High electron gain enthalpy values; oxygen's electron gain enthalpy is less negative than sulphur.
6. Oxidation states show −2 mostly; oxygen can show +2 and −1 in special compounds.
7. Hydrides are angular and show decreasing bond angles and stability down the group.
8. All show allotropy and form various oxides and oxoacids.
9. Sulphur and selenium show puckered ring molecules; heavier elements have stronger van der Waals forces, leading to a solid state under normal conditions.