Ch 1 · Properties of Metals · IGCSE Chemistry 0620
Topic 1 of 6 in Metals — IGCSE Chemistry 0620 — 58 lessons.
Introduction
Roughly three-quarters of the elements are metals, and almost everything built, wired or driven depends on them. This lesson sets out the physical properties that separate metals from non-metals, the three general chemical reactions of metals that examiners expect you to write as balanced equations, and the habit of linking a named property to a named use. It underpins the whole of the Metals topic, from the reactivity series to extraction.
Key ideas — Physical properties of metals and non-metals
Metals and non-metals are compared on five physical properties. Learn them as a pair of lists.
🧑🏫 Teacher's explanation
Imagine a crowded ballroom where everyone is holding hands in a rigid grid. If you try to push through, the group breaks apart (this is like a brittle non-metal). Now, imagine that same ballroom, but everyone is holding hands loosely while a swarm of tiny, fast-moving bees flies between them. The people can slide past each other without letting go of the 'energy' of the bees, and the bees can zip from one side to the other carrying messages. This is metallic bonding.
📖 Definitions
🔍 Worked example — Easy
A block of copper has a mass of 159.5 g and a volume of 14.5 cm^3. Calculate its density.
🔍 Worked example — Standard
Explain why metals are good conductors of electricity using the concept of bonding.
🔍 Worked example — Exam-style
Compare the melting points of metals and non-metals in terms of their bonding.
⚠️ Common errors
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🎯 Exam question
(a) Identify the type of element (metal or non-metal). (b) Explain, in terms of structure and bonding, why this element is ductile. [3 marks]
Key ideas — Reactions with dilute acids
Metals above hydrogen in the reactivity series react with dilute hydrochloric or sulfuric acid to form a salt and hydrogen:
🧑🏫 Teacher's explanation
Think of a metal reacting with acid like a crowd of people (the metal atoms) being pushed out of a room by a group of very energetic, aggressive intruders (the hydrogen ions in the acid). As the metal atoms leave the solid structure to join the liquid, they leave behind a 'salt'—which is just a fancy way of saying the metal is now dissolved and floating around in the water.
📖 Definitions
🔍 Worked example — Easy
Write a balanced chemical equation for the reaction between magnesium and dilute hydrochloric acid. Include state symbols.
🔍 Worked example — Standard
A student reacts 0.50 moles of Zinc with excess sulfuric acid. Calculate the volume of hydrogen gas produced at RTP (molar volume = 24 dm^3 mol^-1).
🔍 Worked example — Exam-style
A piece of magnesium ribbon is added to a test tube containing 50 cm^3 of 1.0 mol/dm^3 HCl. Calculate the mass of magnesium used if the reaction goes to completion and all HCl is consumed.
⚠️ Common errors
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🎯 Exam question
Key ideas — Reactions with cold water and with steam
The most reactive metals react with cold water to give a metal hydroxide and hydrogen:
🧑🏫 Teacher's explanation
Think of metal reactivity like a person's energy level. Some people are so hyperactive that they react to anything they touch (like cold water), while others need a massive boost of energy (like hot steam) just to get moving.
📖 Definitions
🔍 Worked example — Easy
Write a balanced chemical equation for the reaction between Calcium and cold water.
🔍 Worked example — Standard
Magnesium reacts with steam to produce magnesium oxide and hydrogen. Write the balanced equation.
🔍 Worked example — Exam-style
Calculate the mass of hydrogen gas produced when 4.6 g of Sodium reacts completely with excess cold water. (Ar: Na=23, H=1)
⚠️ Common errors
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🎯 Exam question
Key ideas — Reactions with oxygen
Most metals burn or tarnish in oxygen to form a metal oxide, which is a basic oxide:
🧑🏫 Teacher's explanation
Think of metal atoms like people in a crowded room who are very generous. They want to get rid of their extra 'stuff' (electrons) to become stable. When you introduce oxygen, it acts like a magnet that pulls those electrons away. Because the metal loses something negative, it becomes a positive ion. This process of losing electrons is called oxidation.
📖 Definitions
🔍 Worked example — Easy
Write a balanced chemical equation for the reaction between magnesium (Mg) and oxygen (O_2) to form magnesium oxide (MgO).
🔍 Worked example — Standard
Calculate the mass of magnesium oxide (MgO) produced when 4.8 g of magnesium (Mg) reacts completely with oxygen. (A_r: Mg = 24, O = 16)
🔍 Worked example — Exam-style
A student heats copper (Cu) in air. The black solid formed is copper(II) oxide (CuO). Write the balanced equation for this reaction and state the oxidation state of copper in the product.
⚠️ Common errors
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🎯 Exam question
Key ideas — Linking properties to uses
An examiner who asks "explain why" a metal is chosen wants a property named and connected to the job it does. A property on its own earns nothing.
🧑🏫 Teacher's explanation
Think of choosing a material for a job like choosing a tool from a toolbox. You wouldn't use a heavy sledgehammer to hang a tiny picture frame, nor would you use a delicate screwdriver to break a brick. In chemistry, every material has a 'personality'—a set of physical and chemical properties.
📖 Definitions
🔍 Worked example — Easy
A manufacturer needs a material for a cooking pan base that transfers heat quickly to food. Which property of copper makes it suitable, and why?
🔍 Worked example — Standard
Explain why aluminium is used for the body of an aircraft instead of iron.
🔍 Worked example — Exam-style
A piece of metal is used for electrical contacts in a computer. It must not react with moisture in the air to ensure the connection remains reliable. Which property is required?
⚠️ Common errors
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🎯 Exam question
(a) Explain why aluminium is suitable for the exterior panels. [2] (b) Explain why copper is suitable for the wiring. [2] [4 marks]
Worked example
Question. A student adds a piece of zinc to dilute sulfuric acid. (a) Describe two observations. [2] (b) Write a balanced symbol equation, with state symbols, for the reaction. [2] (c) Explain, in terms of structure and bonding, why zinc conducts electricity. [2]
🔍 Worked example — Easy
A student observes a reaction between magnesium and dilute hydrochloric acid. State the observations and write the balanced equation including state symbols.
🔍 Worked example — Standard
Explain why copper is used for electrical wiring in terms of its structure and bonding.
🔍 Worked example — Exam-style
Complete and balance the following equation for the reaction of iron with steam: Fe(s) + H_2O(g) ightarrow FeO(s) + H_2(g)
⚠️ Common errors
Common mistakes
Practice
Answers Any three of: metals are good electrical conductors, good thermal conductors, malleable, ductile, have high melting and boiling points, whereas non-metals are poor conductors, brittle and have low melting and boiling points [B1 each, max 3]. (a) Ca(s) + 2H_2O(l) arrow Ca(OH)_2(aq) + H_2(g) [M1 species, A1 balanced with state symbols]; (b) Mg(s) + H_2O(g) arrow MgO(s) + H_2(g) [M1 species, A1 balanced with state symbols]. Copper is a good thermal conductor so heat passes quickly to the food [B1]; the handle would also become too hot to hold, so a poor thermal conductor such as plastic or wood is used [B1]. Fe(s) + 2HCl(aq) arrow FeCl_2(aq) + H_2(g) [M1 species, A1 balanced]; iron is oxidised because each atom loses two electrons to form mathrmFe^2+ [B1].