What are the general physical properties of metals?

Metals are typically shiny when freshly cut, good conductors of heat and electricity, malleable (they can be hammered into shape) and ductile (they can be drawn into wires). Most have high melting and boiling points and high densities. These properties come from the metallic structure, in which positive metal ions are held together by a sea of free-moving electrons, and they are the reason metals are so widely used in construction, wiring and tools.

Why is an alloy often harder and more useful than the pure metal?

An alloy is a mixture of a metal with one or more other elements. In a pure metal the atoms are the same size and arranged in regular layers that can slide over one another, which makes the metal soft. In an alloy the different-sized atoms disrupt these layers, so they cannot slide as easily, making the alloy harder and stronger. Steel, an alloy of iron with carbon, is a common example.

What is the reactivity series and how is it used?

The reactivity series is a list of metals in order of how reactive they are, from very reactive metals such as potassium and sodium down to unreactive ones such as copper, silver and gold. It is used to predict reactions: a more reactive metal will react more vigorously with water and acid, and a more reactive metal will displace a less reactive one from a solution of its salt. Hydrogen and carbon are often placed in the series as reference points.

How does a metal's reactivity decide how it is extracted?

The more reactive a metal, the harder it is to separate from its ore, so a more energetic method is needed. Very reactive metals such as aluminium are extracted by electrolysis of their molten ores. Metals of middling reactivity such as iron and zinc are extracted by reduction with carbon, for example iron in the blast furnace. Very unreactive metals such as gold are found uncombined in the ground and need only physical separation.

How is Metals and Reactivity assessed in N(A)-Level Science 5107?

It is examined in the two Chemistry papers. Paper 3 (multiple choice, 20 marks) tests the order of the reactivity series, predicting displacement, and matching extraction methods to reactivity. Paper 4 (structured, 30 marks) asks you to predict and explain reactions of metals with water or acid, describe the extraction of iron, and explain rusting and its prevention. There is no separate practical paper.

SingaporeChemistry

Metals and Reactivity (Singapore N(A)-Level Science Chemistry 5107): the properties of metals and alloys, the reactivity series and displacement, and how reactivity decides the way a metal is extracted and how it corrodes

A Singapore N(A)-Level Science Chemistry (SEAB 5107) overview of Metals and Reactivity. The general physical properties of metals, why alloys are often harder and more useful than pure metals, the reactivity series and how it predicts displacement, and how a metal's reactivity decides its extraction method and its tendency to corrode, with links to every dot point.

Generated by Claude Opus 4.85 min readSEAB-5107Updated 2026-06-13

Reviewed by: AI editorial process; not yet individually human-reviewed

Jump to a section

What this topic is really about
Properties of metals and alloys
The reactivity series
Extraction and corrosion of metals
How this topic is examined
Check your knowledge

What this topic is really about

Metals and Reactivity is built around one organising idea: the reactivity series. Once you know the order of the metals, you can predict how each one reacts, why an alloy is useful, how a metal is extracted, and how fast it corrodes. This guide ties the three dot points together and links to each one for the worked answers and practice.

The complete set of dot-point pages for this topic lives at /sg-n-level/chemistry/syllabus/metals-and-reactivity.

Properties of metals and alloys

Properties of metals and alloys sets out the general physical properties of metals (shiny, good conductors, malleable, ductile, mostly high melting points) and explains why alloying makes a metal harder. The different-sized atoms in an alloy stop the layers sliding, so the alloy is stronger than the pure metal.

The reactivity series

The reactivity series is the order of metals from most to least reactive. It lets you compare how metals react with water and acid and predict displacement: a more reactive metal pushes a less reactive one out of a solution of its salt.

Extraction and corrosion of metals

Extraction and corrosion of metals links reactivity to how a metal is obtained and how it decays. Reactive metals such as aluminium need electrolysis; middling metals such as iron are reduced by carbon in the blast furnace; unreactive metals such as gold are found uncombined. The same page covers rusting, which needs both oxygen and water, and how to prevent it by barrier methods or sacrificial protection.

How this topic is examined

Know the series order. From potassium down to gold, with carbon and hydrogen as reference points, so you can predict reactions quickly.
Justify displacement with reactivity. State which metal is more reactive, then give the reaction and the colour change.
Link extraction to reactivity. More reactive means electrolysis; middling means reduction with carbon; unreactive means found native.

Check your knowledge

A mix of recall, reasoning and prediction questions covering Metals and Reactivity. Attempt them under timed conditions, then check against the solutions.

State three general physical properties of metals. (3 marks)
Explain, in terms of atoms and layers, why an alloy is harder than the pure metal. (2 marks)
An iron nail is placed in copper(II) sulfate solution. State what is observed and why. (3 marks)
State the method used to extract aluminium and explain why this method is needed. (2 marks)
State the two substances needed for iron to rust, and one method to prevent rusting. (3 marks)

Solutions

Q1: Any three of: shiny (lustrous), good conductor of electricity, good conductor of heat, malleable, ductile, high melting point, high density.
Q2: In a pure metal the identical atoms form regular layers that can slide over one another, so it is soft. In an alloy the different-sized atoms disrupt the layers so they cannot slide easily, making the alloy harder.
Q3: The blue colour of the solution fades and a red-brown coating of copper forms on the nail. Iron is more reactive than copper, so it displaces copper from the solution, forming iron(II) sulfate and copper metal.
Q4: Aluminium is extracted by electrolysis of its molten ore. Aluminium is too reactive to be extracted by reduction with carbon, so the more energetic method of electrolysis is needed.
Q5: Iron rusts when both oxygen and water are present. Rusting can be prevented by coating the iron (for example painting, oiling or galvanising) or by sacrificial protection with a more reactive metal.

Sources & how we know this

Singapore-Cambridge GCE Normal (Academic) Level Science (Physics, Chemistry) and Science (Chemistry, Biology) (Syllabus 5107) — Singapore Examinations and Assessment Board (2026)
Cambridge Assessment International Education, working with SEAB on the Singapore-Cambridge GCE N(A)-Level — Cambridge Assessment International Education (2026)