Chemical properties of Group 16 elements

Trends in chemical reactivity of group 16 elements

1. The metallic character increases as we descend the group. Oxygen and sulphur are typical nonmetals. Selenium (Se) and Te are metalloids and are semiconductors. Polonium is a metal.

2. Tendency to form multiple bond decreases down the group.
Example O=C=O is stable, S=C=C is moderately stable, Se=C=Se decomposes readily and Te=C=Te is not formed.

3. Formation of Hydrides

All the elements of group 16 form hydrides of the type H₂M (where M=O,S,Se,Te or Po). The stability of hydrides decreases as we go down the group. Except H₂O, all other hydrides are poisonous foul smelling gases. Their acidic character and reducing nature increases down the group. All these hydrides have angular structure and the central atom is in sp³ hybridisation.

4. Formation of Halides
Element of group 16 form a large number of halides. The compounds of oxygen with fluorine are called oxyfluorides because fluorine is more electronegative than oxygen (example OF₂).

The main types of halides are
1. Monohalides of the type M₂X₂
2. Dihalides of the type MX₂
3. Tetrahalides of the type MX₄
4. Hexahalides of the type MX₆

5. Formation Of Oxides
Group 16 elements mainly form three types of oxides.
1. Monoxides: Except Selenium (Se), all other elements of the group form monoxides of the type MO (Example SO)

2. Dioxides: All the elements of group 16 form dioxides of the type MO₂ (Example SO₂)

3. Trioxides: All the elements of the group form trioxides of the type MO₃