Metals and Non-metals
FoundationMetals are lustrous, malleable, ductile and conduct heat and electricity; non-metals are mostly dull, brittle and poor conductors. Properties decide uses.
- General metal properties: lustre, malleability, ductility, electrical and thermal conduction.
- Non-metals are mostly dull, brittle and poor conductors.
- Remember the exceptions: mercury is a liquid metal; graphite is a conducting non-metal.
文體小知識：科普知識文章用生活實例解釋科學概念，先看現象再講原理，讀完就能解釋日常見到的東西。
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1Metals are everywhere in daily life: the drink can at breakfast, the zip on your schoolbag, the doors and window frames of your classroom — all metal products. Their shared metallic feel, a shiny surface and a cool touch, comes from the unique properties of metals.
2Scientists divide elements into metals and non-metals. Metals are lustrous, can be hammered into sheets and drawn into wires, and conduct both electricity and heat well. Non-metals are mostly dull, brittle and poor conductors. Iron, copper and aluminium are the three most common metals, while sulphur and carbon (such as charcoal) are typical non-metals.
3The uses of metals follow directly from their properties: copper conducts and is ductile, so it is ideal for wires; aluminium is light and resists corrosion, so aircraft bodies and drink cans are made of it; iron is hard and strong, so rails and building frames depend on it.
4Yet every rule has exceptions: mercury is a liquid metal at room temperature, while graphite is a non-metal that conducts electricity. Learning to compare properties and explain uses is the first key to S2 chemistry.
1Summary 重點摘要
Metals are lustrous, malleable, ductile and conduct heat and electricity; non-metals are mostly dull, brittle and poor conductors. Properties decide uses.
2Vocabulary cards Vocabulary
A group of elements that are lustrous, good conductors of heat and electricity, and can be hammered into shape, e.g. iron, copper and aluminium.
An element without metallic properties — mostly dull, brittle and a poor conductor, e.g. sulphur and carbon.
The ability of a metal surface to reflect light; freshly polished metals shine brightly.
The property of being hammered or rolled into thin sheets without breaking.
The property of being drawn into thin wires without breaking, like copper wire.
A material that lets electricity or heat pass through it; metals are common conductors.
A material that does not allow electric current to flow through it, such as plastic and rubber.
A pure substance made of only one kind of atom, which cannot be broken down by chemical means.
The ability of a material to resist scratching or denting; diamond is the hardest natural material known.
3Step by step Steps
- Two big familiesElements are the basic building materials of matter and can be sorted into two great families: metals and non-metals. Line up an iron nail, copper wire, aluminium can, sulphur powder and charcoal: the first three are shiny and conduct electricity, so they are metals, while the last two are dull and brittle non-metals. This classification gives a clear framework for later work on properties and reactions, and the two families are put to very different uses in the laboratory and in daily life.
- Look: lustreMetal surfaces reflect light and look shiny — this is called metallic lustre. A freshly polished steel ruler gleams and a copper coin glitters after cleaning, while sulphur powder stays dull yellow and charcoal is black with no shine, so lustre is the quickest visual test. Jewellery is made of gold and silver because their shine lasts, yet appearance alone is not enough and should be checked against other properties.
- Test: malleability and ductilityMetals can be hammered or rolled into thin sheets without shattering — malleability — and drawn into fine wire without snapping — ductility. Aluminium foil is made by repeatedly rolling an ingot, and copper wire is made by drawing copper thinner and thinner. Sulphur, in contrast, shatters into powder when struck, showing neither property. These properties let metals take on many shapes and are widely applied in construction and electronic products.
- Test: conduction of electricityConnect a copper wire in a circuit and the bulb lights at once; swap in a plastic ruler and it stays dark, showing that metals are good conductors while plastics are insulators. Charged particles move freely inside metals, which is why copper is widely used for wires. Note the exception: graphite is a non-metal that conducts, so it serves as electrodes. A cable with a copper core and a plastic sheath is exactly a conductor and an insulator working together.
- Test: conduction of heatMetals conduct heat quickly: put a metal spoon and a plastic spoon into hot soup together and the metal handle soon becomes hot while the plastic one barely warms, because heat travels rapidly through the metal. This explains why pan handles are plastic to prevent burns, while pan bodies are metal for fast, even cooking. Computer heat sinks made of aluminium or copper use the same property to carry heat away.
- Common metals and their usesIron is hard and strong, used for rails and gates, but it rusts easily, so its surface is oiled or galvanised for protection; copper conducts electricity and heat excellently, making it the usual choice for wires and pan bases; aluminium is light and corrosion-resistant, ideal for drink cans and window frames. Every metal's uses follow from its properties, and engineers choose accordingly — gold and silver, being chemically stable, are also used for jewellery and electronic contacts.
- Exceptions existRules help us classify, but exceptions matter just as much: mercury is a metal yet the only one liquid at room temperature, and it expands noticeably when warmed, so it is used in thermometers; graphite is a non-metal yet combines conductivity with lustre, serving as electrodes and pencil leads. Scientists have discovered many new materials by studying such exceptions, so learning science means remembering both the rules and the special cases.
4Diagrams Diagrams
5Worked example Example
Example: aluminium is used for drink cans and aircraft bodies. Explain both uses in terms of metal properties.
- Aluminium has low density — it is light, ideal for aircraft that must reduce weight.
- Aluminium is very malleable — it can be rolled into thin, sealed can walls.
- It forms a dense oxide layer in air — corrosion-resistant, so drinks rarely react with the can.
- It also conducts heat well — which is why it is common in cookware too.
- Answer: Aluminium is light, malleable and corrosion-resistant — perfect for aircraft bodies (light yet strong) and drink cans (rolled thin, does not rust).
6Common mistakes Mistakes
7Quick check Quick check
Q1Which is a general property of metals? A. brittle B. conducts electricity C. dull
Q2Which two properties make copper ideal for wires?
Q3Graphite is a non-metal. Which metal-like property does it have?
Q4Why are pan handles made of plastic?
Q5Name three common metals and one use of each.
8Recap Recap
- General metal properties: lustre, malleability, ductility, electrical and thermal conduction.
- Non-metals are mostly dull, brittle and poor conductors.
- Remember the exceptions: mercury is a liquid metal; graphite is a conducting non-metal.
- Typical uses: iron for structures, copper for wires, aluminium for cans and aircraft.
- Uses come from properties: state the property first, then explain the use.