Cambridge IGCSE Coordinated Sciences · Properties of Matter

Metals vs Non-metals

Most metals share a recognisable set of properties — but chemistry loves exceptions. Work through this lesson to find out what's typical, and what isn't.

Metal property Non-metal property Exception
PART A

Thermal Conductivity

Heat flows easily through metals. You already know this from everyday life — even if you haven't put a name to it yet.

Think first 🤔 — Which of the objects below would you expect to get hot quickly when placed on a stove? Tap each one to decide.
🥘
Metal saucepan
Yes — conducts heat well
🪵
Wooden handle
Non-metal — stays cool
🍴
Steel fork
Yes — metal conducts
🧴
Plastic bottle
Non-metal — poor conductor
🔑
Metal key
Conducts heat to your hand
🧱
Ceramic mug
Poor conductor — stays cool
⬢ Metals

Good thermal conductors. Free electrons carry kinetic energy rapidly through the material. Saucepans, radiators, and heat sinks are all metal for this reason.

◯ Non-metals

Generally poor thermal conductors (insulators). No free electrons — energy is transferred more slowly through vibrating bonds only.

⚠ Notable Exception

Diamond — a non-metal form of carbon — is actually the best thermal conductor of any known material at room temperature. Its rigid covalent lattice transmits vibrations extremely efficiently, despite having no free electrons. This makes it useful in cutting tools and electronics cooling.

PART B

Electrical Conductivity

Metals are electrical conductors because of their structure. Recall from metallic bonding: a sea of delocalised electrons is free to move and carry charge.

DELOCALISED ELECTRONS →
Free electrons flow through the metal wire, carrying electrical charge
Which metals are used in wires? Not all metals are equally good. Reveal the answer below.
Metal Relative conductivity Typical use
Silver (Ag) Electronics (expensive)
Copper (Cu) House wiring, PCBs ✓
Gold (Au) Connector pins
Aluminium (Al) Power cables ✓ (light)
⬢ Metals

Conduct electricity in solid and liquid state. Free electrons carry the charge. Copper and aluminium dominate real-world wiring.

◯ Non-metals

Generally non-conductors (insulators). Used as cable sheaths and plug casings for this reason — they keep electricity in the wire.

⚠ Notable Exception

Graphite — another form of carbon — conducts electricity. Each carbon atom bonds to three others in layers, leaving one electron per atom delocalised between the layers. These mobile electrons allow graphite to conduct. It's used in electrodes.

PART C

Malleability & Brittleness

Students often muddle malleable and brittle. The interactive below should fix that. Try bending each material.

Metal
Can be hammered or bent into shape
Solid Non-metal
Shatters when struck or bent
⬢ Metals — Malleable & Ductile

Malleable: can be hammered into flat sheets. Ductile: can be drawn into wires. The layers of metal ions can slide over each other without breaking bonds, because the electron sea adapts.

◯ Solid Non-metals — Brittle

When a force is applied, layers of atoms shift and bring like-charges next to each other, causing repulsion — the material snaps. Sulfur, phosphorus, and iodine are all brittle solids.

⚠ Important: Most non-metals are not even solid at room temperature — nitrogen, oxygen, chlorine, and hydrogen are all gases. Solid non-metals (like sulfur) are the brittle ones.
PART D

Melting & Boiling Points

Metals generally have high melting points because a lot of energy is needed to break the strong metallic bonds. Non-metals are the opposite — many are already gases at room temperature.

Melting Points (°C) — click to animate
⬢ Metals

Most have high melting points. Iron melts at 1538°C; tungsten, used in light bulb filaments, melts at an extraordinary 3422°C. Strong metallic bonds require a lot of energy to overcome.

◯ Non-metals

Typically low melting points. Nitrogen melts at −210°C, bromine at −7°C. Most are already gases at 25°C. Simple molecular structures — weak intermolecular forces only.

Room temperature check: At 25°C, most metals are solid (only mercury is a liquid). Most non-metals are gases (oxygen, nitrogen, chlorine, hydrogen…). Which state do you think of first when someone says "non-metal"?
✦ Check your understanding
1. A student says "non-metals are always poor thermal conductors." What is wrong with this statement?
2. Why are metals electrical conductors?
3. Which non-metal conducts electricity and is used in electrodes?
4. A material shatters when hammered. What does this tell you about it?
5. Tungsten is used in light bulb filaments that reach 2500°C in operation. What property does this demonstrate?
6. At room temperature (25°C), which of the following statements is correct?
0/6
▶ Watch & Research

Go deeper

Two videos to consolidate what you've learned, followed by independent research tasks. Watch first, then choose a task.

VIDEO 1 OF 2
Metals & Non-metals: Electron Arrangement & Properties
Cognito · 2025 · ~8 min
Covers the four general properties from this lesson plus how electron arrangement explains the differences. Good exam-focused summary.
Watch questions — answer as you go
  1. How does the video explain why metals conduct electricity, in terms of electrons? Does it match what you learned here?
  2. The video mentions the periodic table location of metals and non-metals. Sketch the dividing line from memory after watching.
  3. Note down any property or example mentioned in the video that wasn't covered in this lesson.
VIDEO 2 OF 2
What Are Allotropes? — Non-Metals
FuseSchool · ~4 min
Focuses on diamond and graphite — the two exceptions from this lesson. Explains their structures and why they break the usual non-metal rules.
Watch questions — answer as you go
  1. What is an allotrope? Give the definition in your own words after watching.
  2. The video explains graphite's structure in detail. Draw a simple diagram of the layers from memory after watching.
  3. Why is diamond hard but graphite soft, even though both are pure carbon? Explain using the video's structural diagrams.
🔍 Research Tasks

Choose one (or more) to investigate

These tasks take you beyond the lesson content. Use reliable sources — try BBC Bitesize, RSC ChemSpider, or your textbook. Aim for a written response of at least a paragraph per question.

Core
💎
The Carbon Paradox
Diamond and graphite are both made entirely of carbon atoms, yet one is the hardest natural material and one of the best thermal conductors, while the other is soft and conducts electricity. Research the structures of both allotropes at the atomic level.
  1. How many covalent bonds does each carbon atom form in (a) diamond and (b) graphite? What shape does each arrangement make?
  2. What are the delocalised electrons in graphite and where do they come from?
  3. Why can graphite layers slide over each other, but diamond cannot be scratched by almost anything?
  4. What is graphene? How is it related to graphite and why is it scientifically exciting?
Suggested sources: RSC.org, BBC Bitesize Chemistry (allotropes), your Cambridge textbook Chapter on carbon chemistry.
Core
⚡
Why Copper, Not Silver?
Silver is a better electrical conductor than copper — yet your house is wired with copper. Research the real-world trade-offs behind material selection for electrical wiring.
  1. List three properties a material needs to be a good electrical wiring material (not just conductivity).
  2. Why is aluminium used in high-voltage power transmission cables instead of copper, despite being a worse conductor?
  3. What is resistivity? Find the resistivity values for copper, aluminium, and silver and compare them.
  4. Research one recent development in superconducting materials. What temperature do current superconductors require, and why is this a practical problem?
Suggested sources: IOP Physics.org, Engineering Toolbox, New Scientist articles on superconductors.
Extension
🌡
The Outliers: Mercury & Bromine
At room temperature, mercury is the only metal that is liquid, and bromine is the only non-metal liquid. Both break the "typical" pattern. Investigate why.
  1. Mercury's low melting point (−39°C) is unusual for a metal. Look up the relativistic effects that explain this — write a brief summary in plain language.
  2. Bromine boils at 59°C — just above room temperature. What type of intermolecular forces hold bromine molecules together in the liquid?
  3. Mercury is highly toxic. Research one historical case where mercury poisoning affected a large population or a famous individual.
  4. Find two current industrial or scientific uses of liquid mercury and evaluate whether the risks justify the uses.
Suggested sources: RSC.org element pages, Wikipedia (for relativistic effects — check the citations), Chemistry World magazine.
Extension
🔩
Metalloids: The In-Between Elements
Silicon, germanium, arsenic, antimony — these elements sit on the "staircase" line between metals and non-metals on the periodic table. They're neither fully one nor the other. Research this category.
  1. List five elements generally classified as metalloids and give one property each that is "metal-like" and one that is "non-metal-like".
  2. Silicon is a semiconductor. Explain in simple terms what a semiconductor is and why it is more useful than a pure conductor or insulator for electronics.
  3. Why is the metal/non-metal classification described as "general" rather than exact? Use metalloids and the exceptions from this lesson in your answer.
  4. Research the "silicon revolution" — how did silicon-based semiconductors change human technology? Give three specific examples.
Suggested sources: BBC Bitesize, Khan Academy Chemistry, Science Museum Group articles on the silicon chip.
Real World
🌊
Metals in the Ocean
Seawater contains dissolved metal ions and non-metal compounds — and it corrodes most metals aggressively. Marine environments present unique materials challenges. Research the chemistry of metals at sea.
  1. Why does salt water corrode metals faster than fresh water? Explain using the concept of electrical conductivity.
  2. Titanium is used in submarine hulls and offshore structures despite being expensive. What properties make it ideal for marine use?
  3. Research "sacrificial anodes" — what are they, what metal are they usually made from, and how do they protect ship hulls?
  4. Deep-sea polymetallic nodules contain manganese, nickel, copper, and cobalt. Research the debate around deep-sea mining: what are the arguments for and against extracting these metal deposits?
Suggested sources: NOAA Ocean Service, National Geographic, BBC Science (deep-sea mining debates), your Cambridge textbook (corrosion section).
Real World
🏎
Materials in Extreme Environments
Formula 1 cars, spacecraft re-entry shields, and jet turbine blades all require materials that behave well far outside normal conditions. Research how engineers exploit the properties of metals and non-metals in extreme engineering.
  1. Tungsten has the highest melting point of all metals (3422°C). Find two specific engineering applications that rely on this property and explain why no other material would work as well.
  2. Carbon fibre (a non-metal material) is used in F1 chassis and aircraft parts. List its key properties and explain why it outperforms metals in these applications.
  3. The Space Shuttle's heat shield tiles were made of silicon dioxide — a non-metal compound. Research how they worked and why metals could not be used instead.
  4. Research "superalloys" — what are they, which metals are they typically based on, and where are they used?
Suggested sources: NASA Materials Science articles, Engineering.com, F1 Technical (f1technical.net), IOM3 (Institute of Materials).
✦ Summary Task

Create your own revision resource

You've worked through the lesson — now consolidate it. Choose a format below and use the scaffold provided to produce your own summary of metals vs non-metals properties.

🪧
Poster
A single-page visual for the classroom wall
📊
Infographic
Icons, data, and short labels — no long sentences
📋
Comparison Table
A structured grid to compare properties side by side
🃏
Flashcard Set
Six key facts — one per card, front and back
VISP · Sixth Form Science · Properties of Metals & Non-Metals