4.7	Transition Elements

Position of Transition Elements

• Position in the Periodic Table from Group 2 until Group 12.
• The transition metal is metal that has some characteristics:
  • High density
  • High hardness
  • Silvery surface
  • High tensile strength
  • High conductivity
  • Ductile and malleable
  • High melting point
  • High boiling point

 

Special properties of transition elements

• Transition elements have more than one oxidation numbers

Oxidation  number	Compound
Chromium, Cr
+3	Chromium(III) chloride, \(CrCl_3\)
+6	Potassium dichromate(VI), \(K_2Cr_2O_7\)
Manganese, Mn
+2	Manganese(II) chloride, \(MnCl_2\)
+4	Manganese(IV) oxide, \(MnO_2\)
+7	Potassium manganate(VII), \(KMnO_4\)
Iron, Fe
+2	Iron(II) sulphate, \(FeSO_4\)
+3	Iron(III) chloride, \(FeCl_3\)
Copper, Cu
+1	Copper(I) oxide, \(Cu_2O\)
+2	Copper(II) oxide, \(CuO\)
Nickel, Ni
+2	Nickel(II) sulphate, \(NiSO_4\)
+3	Nickel(III) chloride, \(NiCl_3\)

 

 

• Transition elements form coloured compounds.

Ion	Colour of  solution
Chromium, Cr
Chromium(III) ion, \(Cr^{3+}\)	Green
Dichromate(VI) ion, \(Cr_2O_7^{2-}\)	Orange
Manganese, Mn
Manganese(II) ion, \(Mn^{2+}\)	Pink
Manganate(VII) ion, \(MnO_4\,^-\)	Purple
Iron, Fe
Iron(II) ion, \(Fe^{2+}\)	Green
Iron(III) ion, \(Fe^{3+}\)	Brown
Copper, Cu
Copper(II) ion, \(Cu^{2+}\)	Blue
Nickel, Ni
Nickel(II) ion, \(Ni^{2+}\)	Green

 

• Transition elements function as a catalyst to increase the rate of reaction.
  • The use of iron as the catalyst in the Haber process to produce ammonia.
  • \(\,\\N_2 + 3H_2 \xrightarrow[]{Fe} 2NH_3\)

 

Uses of Transition Elements in the Industry

Element or compound	Uses
Iron, Fe	Used as a catalyst in the Haber Process to produce ammonia, \(NH_3\) Used to build bridges
Platinum, Pt	Used as a catalyst in the Ostwald Process to produce nitric acid, \(HNO_3\)
Vanadium(V) oxide, \(V_2O_5\)	Used as a catalyst in the Contact Process to produce sulphuric acid, \(H_2SO_4\)
Nickel, Ni or Platinum, Pt	Used as a catalyst in the hydrogenation process on vegetable oils to produce margarine
Manganese, Mn	Used to make stained glass windows
Titanium, Ti	Used to make paints