SPM Form 4 Chemistry Notes — Chapter 4『4.6』Transition Elements

4.6 Transition Elements

 Transition metal is a block of metallic elements in between Group 2 and 13 in the Periodic Table.

 They are much less reactive than the alkali metals.

 They do not react as quickly with water or oxygen as alkali metals.

Some general physical characteristics

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

✔ high melting and boiling points

✔ hard, high density

✔ high tensile strength

✔ high electrical conductivity

✔ shinny surfaces, ductile, malleable

✔ good conductor of heat

［Tensile strength］▷ the ability of metals to stay in their shape without breaking when a force is applied to it.

［Ductile］▷ the ability of metals to be stretched into wires without cracking or breaking them

［Malleable］▷ the ability of metals to be bent into a new shape.

High melting and boiling points

▶ The bond between atoms of metals is called metallic bond and usually it is a very strong bond.

▶ Thus all the transition metals have high melting point and boiling point

Form coloured compounds and ions

✈ Transition elements tend to form coloured compounds either in solid form or dissolved in a solvent.

Ions	Colour
Fe2+	Light green
Fe3+	Brown
Ni2+	Green
Cr3+	Green
Mn2+	Light pink
Cu2+	Blue
Co2+	Pink
MnO4-	Purple
CrO42-	Yellow
Cr2O72-	Orange

Catalytic properties

➷ A catalyst is a substance that speeds up a reaction but itself does not change chemically after a reaction

➷ Many transition metals are used directly as catalysts in industrial chemical processes.

Transition elements / its compound	Uses
Platinum	Ostwald Process in the manufacture of nitric acid
Nickel	Catalyst for “hydrogenation” in the margarine industry
Iron powder	Haber Process in the manufacture of ammonia
Vanadium(V) oxide	Contact Process in the manufacture of sulphuric acid

Variable oxidation state

✎ A transition elements can have a variable oxidation state, which means it can form more than one ion.

✎ for example, iron(II), Fe²⁺ and iron(III), Fe³⁺ , copper(I), Cu⁺ and copper(II), Cu²⁺

Forming a complex ions

◆ Transition elements can form complex ions.

◆ A complex ion is a polyatomic ions (positive or negative) consisting of a central metal ion with other group bonded to it.