Transition Metals

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CognitoTransition metals — properties and uses

Key facts & methods

Properties of transition metals

Transition metals are in the central block of the periodic table (Groups 3–12, periods 4–7).
Examples: iron (Fe), copper (Cu), zinc (Zn), nickel (Ni), titanium (Ti), chromium (Cr), manganese (Mn).
Properties: high melting points (except mercury). High density. Strong. Good conductors of heat and electricity. Malleable and ductile.
Key distinction from Group 1: transition metals are much less reactive, harder, higher melting points, higher density.
Most transition metals form coloured compounds: iron(II) = pale green, iron(III) = orange-brown, copper(II) = blue.

Variable oxidation states and catalysis

Transition metals can form ions with different charges (variable oxidation states).
E.g. iron forms Fe²⁺ (iron(II)) and Fe³⁺ (iron(III)).
Copper forms Cu⁺ and Cu²⁺. Chromium forms Cr²⁺, Cr³⁺, Cr⁶⁺.
Catalysts: transition metals and their compounds are excellent catalysts.
Iron: catalyst in the Haber process (N₂ + 3H₂ ⇌ 2NH₃).
Manganese dioxide (MnO₂): catalyst in decomposition of hydrogen peroxide.
Nickel: catalyst in hydrogenation of vegetable oils.

Uses of transition metals

Iron: structural steel, bridges, vehicles.
Copper: electrical wiring (high conductivity), water pipes (malleable, resistant to corrosion).
Titanium: aircraft and surgical implants (strong, low density, corrosion resistant, biocompatible).
Chromium: stainless steel (alloy with iron — corrosion resistant).
Platinum: catalytic converters in cars (converts CO and NOₓ to CO₂ and N₂).

Exam questions — 5 questions · 12 marks · AQA 8462 style

1 markTransition metal propertyAQA 8462 style

Which of the following is a property shared by most transition metals but NOT by Group 1 metals?

A They react vigorously with cold water

B They are soft solids that can be cut with a knife

C They form coloured compounds and can act as catalysts

D They have low density and float on water

1 markCatalyst identificationAQA 8462 style

Which transition metal is used as a catalyst in the Haber process?

A Copper

B Iron

C Platinum

D Nickel

3 marksCompare propertiesAQA 8462 style

Sodium (Group 1) and iron (transition metal) are both metals. Compare their physical properties and reactivity. (3 marks)

Hint: Compare: melting point, hardness/density, reactivity with water. Sodium and iron should contrast sharply on all three.

+30 XP

3 marksVariable oxidation statesAQA 8462 style

Iron can form two different ions: Fe²⁺ and Fe³⁺. (a) What is this property called? (b) Describe how you could distinguish between iron(II) sulfate solution and iron(III) chloride solution using sodium hydroxide solution. (3 marks)

Hint: (a) Variable oxidation states. (b) NaOH test: Fe²⁺ gives pale green precipitate, Fe³⁺ gives orange-brown precipitate.

+30 XP

Properties of transition metals

Variable oxidation states and catalysis

Uses of transition metals

Module complete! 🎉