4.7.1 The Transition Elements

1. The transition metal is a block of metallic elements in between Groups 2 and 13 in the Periodic Table.
2. They are much less reactive than the alkali metals.
3. They do not react as quickly with water or oxygen as an alkali metal.

General Physical Characteristics

All transition elements are metals. Therefore they have all the physical properties of metal such as:

1. high melting point and boiling point
2. hard,
3. high density,
4. high electrical conductivity,
5. high tensile strength,
6. shinny surfaces,
7. ductile
8. malleable,

High Melting Point and Boiling Point

1. The bond between atoms of metal is called metallic bond and usually, it is a very strong bond.
2. Thus all the transition metals have high melting points and boiling points.
3. For example, iron melts at 1535°C and boils at 2750°C.
4. Mercury is a transition metal, but with unusual low melting point ( − 39°C).

Special Properties of Transition Elements

Form Coloured Compounds and Ions in Solute

1. Transition elements tend to form coloured compounds either in solid form or dissolved in a solvent.
2. The table below shows the colours of some aqueous solutions of ions of transition elements.

Catalytic Properties

1. Transition elements or their compounds have catalytic properties.
2. A catalyst is a substance that speeds up a reaction but it itself does not change chemically after a reaction.
3. Many transition metals are used directly as catalysts in industrial chemical processes.

Variable Oxidation State

1.  The transition metal can have a variable oxidation state, which means it can form more than one ion.
2. For example, iron(II), Fe²⁺ and iron(III) Fe³⁺; copper(I), Cu⁺ and copper (II) Cu²⁺.

Forming Complex Ions

1. Transition elements can form complex ions.
2. A complex ion is a polyatomic ion (positive or negative) consisting of a central metal ion with other groups bonded to it.