Transition metalsIB MYP Chemistry: Revision notes
Section 1
What are transition metals?
The transition metals are the block of metals in the middle of the periodic table, between Group 2 and Group 3 (for example titanium, chromium, manganese, iron, nickel, copper and zinc).
They are the metals you meet in everyday life: iron in steel, copper in wires and pipes, and nickel in coins. Their properties are quite different from those of the Group 1 metals.
Section 2
Physical properties
Compared with Group 1 metals, typical transition metals have:
- a high density (iron sinks in water, sodium floats)
- a high melting point (iron melts at about 1540 °C; sodium at about 98 °C)
- strength and hardness (they are used to make bridges, tools and engines)
They are also much less reactive than Group 1 metals: iron reacts only slowly with oxygen and water, and copper hardly reacts at all.
In a comparison question, name the property and give both sides: iron has a higher density than sodium.
Section 3
Coloured compounds
Many compounds of transition metals are coloured, while compounds of Group 1 and Group 2 metals are usually white or colourless.
- copper(II) compounds: blue (copper(II) sulfate solution)
- iron(II) compounds: pale green
- iron(III) compounds: orange-brown
The colour can help to identify the metal ion in a solution.
Section 4
Variable charges
A Group 1 metal always forms a 1+ ion. Transition metals can form more than one ion with different charges. Iron forms Fe²⁺ and Fe³⁺, and copper can form Cu⁺ and Cu²⁺.
The charge is shown by a Roman numeral in the name:
- iron(II) chloride, FeCl₂, contains Fe²⁺
- iron(III) chloride, FeCl₃, contains Fe³⁺
The Roman numeral is the charge on the metal ion, not the number of atoms. Iron(III) oxide is Fe₂O₃, with two Fe³⁺ ions.
Section 5
Transition metals as catalysts
A catalyst speeds up a reaction without being used up. Transition metals and their compounds are often good catalysts:
- iron in the Haber process for making ammonia
- nickel in making margarine from vegetable oils
- manganese(IV) oxide for breaking down hydrogen peroxide into water and oxygen
- platinum and rhodium in car catalytic converters
Catalysts save energy and money in industry because reactions work faster at lower temperatures.
Section 6
Examples and uses
- Iron (as steel): buildings, bridges, cars and tools, because it is strong and has a high melting point.
- Copper: electrical wires and water pipes, as it is easy to shape and does not react easily.
- Titanium: aircraft parts and replacement joints, because it is strong and does not corrode.
- Chromium: shiny, protective plating on metals.
- Platinum: catalytic converters and jewellery.
That's the notes covered.
Carry on to the next subtopic.
Exam questions on Transition metals
- A student in Mumbai compares a piece of iron with a piece of sodium. The iron is hard, sinks in water and does not melt in a Bunsen burner flame. The sodium is soft, floats on water and melts easily. She also dissolves copper(II) sulfate in water and sees that the solution is blue.State two physical properties in which transition metals differ from Group 1 metals.2 marks
- Iron forms two different chlorides. A solution of iron(II) chloride is pale green and a solution of iron(III) chloride is orange-brown. A technician is labelling bottles of the two solutions in a school store room.Explain why iron forms two different chlorides.2 marks
- A student investigates whether manganese(IV) oxide, a transition metal compound, speeds up the breakdown of hydrogen peroxide into water and oxygen. She puts 20 cm³ of hydrogen peroxide solution in a flask and measures the volume of oxygen collected in 120 s. Without manganese(IV) oxide she collects 8 cm³. She then repeats the test once with 0.5 g of manganese(IV) oxide powder added and collects 52 cm³.Identify the independent variable, the dependent variable and one control variable.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).