Quick Notes

Quick Notes

Chemistry Chapter 4: Periodic Table of Elements
4.7 Transition Elements
4.7 Transition Elements
CHEMISTRY • Form 4 • Chapter 4: The Periodic Table of Elements

4.7Transition Elements

Transition elements are metallic elements situated between Group 2 and Group 13 in the Periodic Table of Elements. They possess four distinct special characteristics and play an essential role in daily life and industrial chemical processes.

Learning Objectives

  • Determine the position of transition elements in the Periodic Table of Elements.
  • Explain the special characteristics of a few transition elements with examples.
  • List the uses of transition elements in industry.

Special Characteristics and Industrial Uses of Transition Elements

A visual summary of the four special characteristics and their links to industrial processes.

Transition Elements · Group 3 to Group 12

1. Catalysts

Iron in the Haber Process, vanadium(V) oxide in the Contact Process, platinum in the Ostwald Process, nickel/platinum in hydrogenation.

2. Coloured Ions / Compounds

Cu2+ is blue, Fe2+ is green, Fe3+ is brown, Cr2O72− is orange, MnO4− is purple.

3. Multiple Oxidation Numbers

Iron exists as +2 and +3; copper exists as +1 and +2; manganese exists as +2, +4 and +7.

4. Complex Ions

[Cu(NH3)4]2+, [Fe(CN)6]3−, [Fe(CN)6]4−, [Fe(H2O)6]2+.

Brief Explanation

Position, metallic properties and the four special characteristics.

Transition elements are located in Group 3 to Group 12, between Group 2 and Group 13. Examples include chromium, manganese, iron and copper. Scandium and zinc are placed in this block but are not considered transition elements because they do not show the characteristics of transition elements.

General Metallic Properties

  • Solids with shiny surfaces
  • Very hard compared to Groups 1 and 2 metals
  • High densities
  • High melting and boiling points
  • Malleable and ductile

Four Special Characteristics

  • Function as catalysts
  • Form coloured ions or compounds
  • Have more than one oxidation number
  • Form complex ions
Special characteristic Examples
Catalysts Iron in the Haber Process; vanadium(V) oxide in the Contact Process; platinum in the Ostwald Process; nickel/platinum in hydrogenation.
Coloured ions / compounds Cu2+ blue; Fe2+ green; Fe3+ brown; Cr2O72− orange; MnO4− purple.
Multiple oxidation numbers Fe: +2 and +3; Cu: +1 and +2; Mn: +2, +4 and +7.
Complex ions [Cu(NH3)4]2+; [Fe(CN)6]3−; [Fe(CN)6]4−; [Fe(H2O)6]2+.

Try These Questions First

Answer mentally, then check the explanation.

1

Why are scandium and zinc not considered transition elements even though they are located in the d-block area?

Answer: Scandium and zinc are not considered transition elements because both do not show the characteristics of transition elements, such as variable oxidation numbers or forming coloured ions.
2

State the catalyst used and the product formed in the Contact Process.

Answer: The catalyst used is vanadium(V) oxide, V2O5, and the product formed is sulphuric acid, H2SO4.
3

What is Nitinol, and what is its special property and application?

Answer: Nitinol is an alloy of nickel and titanium that can 'remember' its form and return to its original shape after being bent. It is used to make spectacle frames and treat broken bones.

Common Mistakes

Avoid these errors when studying transition elements.

!
Assuming all elements between Group 2 and Group 13 are transition elements, overlooking that scandium and zinc are excluded.
!
Confusing the colour of iron(II) ions, Fe2+ is green, with iron(III) ions, Fe3+ is brown.
!
Mixing up the catalysts for industrial processes: confusing iron in the Haber Process with vanadium(V) oxide in the Contact Process or platinum in the Ostwald Process.
!
Writing incorrect charges or oxidation numbers when naming compounds, such as writing iron sulphate without specifying iron(II) or iron(III).

Common Misconceptions

Compare each misconception with the correct fact.

Misconception

All metals form coloured solutions.

Correct Fact

Main group metals such as Na+, Mg2+ and Al3+ form colourless aqueous solutions. Forming coloured solutions and compounds is a special characteristic of transition elements.

Misconception

A catalyst is consumed or permanently altered in the chemical reaction.

Correct Fact

Transition element catalysts increase the rate of reaction without undergoing any chemical change at the end of the reaction.

Summary

Key facts to remember.

  • Transition elements are placed in Group 3 to Group 12. Scandium and zinc do not show transition element characteristics and are not considered transition elements.
  • General properties: shiny, very hard, high density, high melting and boiling points, ductile and malleable.
  • Four special characteristics: act as catalysts, exhibit variable oxidation numbers, form coloured ions and compounds, and form complex ions.
  • Industrial catalysts include Fe in the Haber Process, V2O5 in the Contact Process, Pt in the Ostwald Process, and Ni/Pt in hydrogenation.
  • Other uses: building bridges (Fe), paints (Ti), stained glass (Mn), and shape-memory alloy spectacle frames and bone treatment (Nitinol).

Quick Activity

Complete all parts before checking your score.

A. Objective Quiz

1

Which of the following pairs of elements are located in the d-block but are not considered transition elements because they do not show the characteristics of transition elements?

2

What catalyst is used in the Contact Process to produce sulphuric acid?

B. Fill in the Blanks

3

In the Haber Process, iron filings act as a catalyst to produce ammonia at an operating pressure of 200–300 atm and a temperature of ______ °C.

4

Aqueous copper(II) ions, Cu2+(aq), produce a ______ colour in solution.

C. Match the Industrial Process with the Catalyst

Drag each process on desktop. On mobile, tap a process and then tap the matching box.

Industrial Process

Haber Process (production of ammonia) Contact Process (production of sulphuric acid) Ostwald Process (production of nitric acid) Hydrogenation of vegetable oils (production of margarine)

Catalyst

1Iron, Fe
2Vanadium(V) oxide, V2O5
3Platinum, Pt
4Nickel, Ni or platinum, Pt
Complete every answer before checking.
 

Keywords

Tap or hover over a term to read its meaning.

Transition elements Catalyst Oxidation number Complex ion Nitinol Haber Process Contact Process Ostwald Process