Lecture 7 – Transition Elements

Transition Elements:

The central block of the Periodic Table consists of Transition metals. They have unique properties like:

1. They have high melting and boiling points.
2. They have high densities.
3. They have variable valencies and thus variable oxidation state.
• Example:
• Iron: Iron exists as Fe²⁺ and Fe³⁺
• Copper: Copper exists as Cu⁺ and Cu²⁺
• Manganese: Manganese exists as Mn²⁺ and Mn⁷⁺
• Chrome: Chrome exists as Cr²⁺ and Cr⁵⁺
4. They form coloured compounds in different oxidation states.
• Example:
• Fe²⁺ = Green coloured compounds
• Fe³⁺ = Brownish orange/rust coloured compounds
• Cu⁺ = Black or white coloured compounds
• Cu²⁺ = Blue coloured compounds
5. Transition metals and their compounds have catalytic properties and are used in various industrial processes; to speed up industrial processes and save cost.

Table 4: Transition metal and their compounds as catalyst

Name of the Process	Detail of the Process	Catalyst used
Harber Process	Industrial manufacture of Ammonia (NH3)	Iron
Contact Process	Industrial manufacture of Sulphuric Acid (H2SO4)	Vanadium(V)Oxide
Hydrogenation of Alkenes	Conversion of Alkenes to Alkanes	Nickle
Hydrogenation of Unsaturated Fats	Manufacture of Margarine	Nickle