Metals, Non-Metals and Metalloids
In 1868, gold-rush prospectors pulled over 3,000 kg of gold nuggets from creeks near Bathurst, NSW, a pure metal that conducted electricity, bent without snapping, and shone like nothing else they'd ever touched.
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Q1 · List three objects in your kitchen or classroom that you think are made of metal. What clues told you so?
Q2 · A pencil "lead" is actually carbon. Why doesn't it feel or behave like the copper wire next to it, even though both are elements?
● Know
- The four main properties of metals (shiny, malleable, ductile, conductive)
- The properties of non-metals (dull, brittle, poor conductors)
- Where the staircase line sits on the periodic table
● Understand
- Why metalloids sit in between metals and non-metals
- Why metal properties make them useful for wires, tools and structures
- Why silicon's "in-between" nature makes it perfect for computer chips
● Can do
- Classify a sample as metal, non-metal or metalloid from its properties
- Match elements (Fe, Cu, Au, S, O, C, Si, Ge, As) to their categories
- Use the staircase line to predict an element's category
- Malleable
- Ductile
- Brittle
- Conductor
- Metalloid
- Lets heat or electricity flow through easily
- Can be hammered into thin sheets
- In-between element on the staircase line
- Can be pulled into a wire
- Snaps or shatters when struck
Twist a copper wire around a pencil, it bends without snapping. Touch it to both terminals of a battery, current flows through it. Tap it with a hammer, it flattens rather than shattering. These observations tell you it's a metal. About three-quarters of all elements are metals, sitting on the left of the periodic table staircase, and sharing this famous set of four properties.
| Property | What it means | Everyday example |
|---|---|---|
| Shiny (lustrous) | A freshly cut metal surface reflects light. | A 50-cent coin, polished aluminium. |
| Malleable | Can be hammered into sheets without breaking. | Aluminium foil pressed paper-thin. |
| Ductile | Can be drawn into long thin wires. | Copper wire inside an extension cord. |
| Good conductor | Lets heat and electricity flow through. | A saucepan base (heat); copper wires (electricity). |
Common metal examples to remember:
- Iron (Fe)used for steel beams, train rails, car bodies.
- Copper (Cu)used for electrical wires and water pipes.
- Gold (Au)used in jewellery and inside computer chips because it doesn't tarnish.
Most metals are also solid at room temperature. The famous exception is mercury (Hg), a liquid metal once used in thermometers.
Metals are , can be hammered into sheets (), pulled into wires () and let electricity flow through them (good ).
Non-metals sit on the right of the staircase line. They are almost the opposite of metals.
| Property | What it looks like |
|---|---|
| Dull | No metallic shine. Sulfur is a dull yellow powder. |
| Brittle | Solids shatter when hit. A piece of sulfur or carbon snaps like chalk. |
| Poor conductor | Heat and electricity do not flow through. (Exception: graphite, a form of carbon, does conduct electricity.) |
| Many are gases | Oxygen, nitrogen, hydrogen, chlorine, at room temperature they are gases. |
Common non-metal examples to remember:
- Sulfur (S)bright yellow powder used to make matches and rubber.
- Oxygen (O)the gas in the air that keeps you alive.
- Carbon (C)the element in pencil leads, charcoal and diamonds.
Right on the staircase line sit a small group of elements called metalloids. They show some metal properties and some non-metal properties, they sit between the two camps.
- Silicon (Si)looks shiny like a metal but shatters like glass. Used in computer chips and solar panels.
- Germanium (Ge)used in old transistors and modern fibre-optic cables.
- Arsenic (As)toxic; was once used in green paints and rat poison.
The most useful metalloid is silicon. It conducts electricity, but only sometimes, and only when scientists "dope" it with tiny amounts of other elements. That switchable conducting is exactly what makes a semiconductor. Every smartphone, laptop and solar panel relies on silicon's in-between behaviour.
Wrong: "Anything shiny must be a metal." Galena (a non-metal compound of lead and sulfur) has a metallic shine but is brittle and a poor conductor. Looks alone aren't enough.
Right: Use multiple properties together, shiny AND malleable AND ductile AND a good conductor, before calling something a metal.
Wrong: "All metals are solid." Mercury is a metal that is liquid at room temperature, and gallium melts in your hand.
Right: Most metals are solid at room temperature, but a few (mercury, gallium, caesium) melt easily. The properties of being shiny and conducting still apply.
Wrong: "Carbon is a metal because graphite conducts electricity." Graphite is a special form of carbon, but carbon itself is a non-metal (dull, brittle, mostly insulating).
Right: Carbon is a non-metal. Graphite is an unusual exception that conducts electricity, but carbon still fails the other metal tests.
Engineers and designers choose materials based on these property categories. A quick tour:
| Job | Element chosen | Why |
|---|---|---|
| Electrical wire | Copper (metal) | Very ductile and a great conductor. |
| Aircraft body | Aluminium (metal) | Light, malleable, doesn't rust quickly. |
| Plastic wire coating | Carbon-based plastic (non-metal) | Poor conductor, stops electricity escaping. |
| Computer chip | Silicon (metalloid) | Semi-conducts electricity, switchable. |
| Gold jewellery | Gold (metal) | Doesn't tarnish; easy to shape. |
So the classification isn't just trivia, it tells you what each element can do for us.
A friend hands you a shiny grey sample that looks like polished metal. You drop it on the bench and it shatters like glass. You touch a battery to it, it conducts electricity only weakly. Predict: is it a metal, a non-metal, or a metalloid? Explain in one sentence, then reveal.
How close was your prediction?
Nice, you spotted that combining shiny + brittle + weak conductor pins down a metalloid.
Good, being surprised is the point. Using one property alone (like shine) is misleading.
At the start of this lesson you were asked: Silicon is shiny like a metal but smashes like glass when you hit it, where does it fit? Did you have a guess for this one?
Now you know about metals, non-metals and metalloids, write a proper answer. Explain where silicon fits and use at least three specific properties to back up your answer.
Q1. List the four main properties of a metal and give one everyday example for each property. (3 marks)
Q2. Classify each element as a metal, non-metal or metalloid, and give one reason for your classification: copper (Cu), oxygen (O), silicon (Si), gold (Au). (4 marks)
Q3. A student says "Anything shiny that conducts electricity must be a metal." Evaluate this claim. Use at least one specific example (e.g. silicon, graphite, galena) to support your answer. (4 marks)
Answers
▾MCQ 1
AMetals are shiny, malleable, ductile and good conductors. B describes non-metals; C and D are mixed.
MCQ 2
CDull and brittle are classic non-metal properties. Sulfur is a yellow non-metal.
MCQ 3
DMetalloids sit right on the staircase line that separates metals (left) from non-metals (right).
MCQ 4
BSilicon is a metalloid. Its switchable conductivity (semiconductor behaviour) is exactly what computer chips need.
MCQ 5
CIron is a metal. Sulfur and oxygen are non-metals; silicon is a metalloid.
Short Answer 1
Model answer: (1) Shiny / lustrousa freshly polished 50-cent coin reflects light. (2) Malleablealuminium foil hammered into thin sheets. (3) Ductilecopper drawn out into a long thin wire inside an extension cord. (4) Good conductora saucepan base conducts heat to cook food, copper wires conduct electricity.
Short Answer 2
Model answer: Copper (Cu) = metal (shiny, ductile, excellent conductor, used in wires). Oxygen (O) = non-metal (a gas at room temperature, does not conduct electricity). Silicon (Si) = metalloid (shiny like metal but brittle; semi-conducts electricity, used in computer chips). Gold (Au) = metal (shiny, malleable, good conductor, used in jewellery and electronics).
Short Answer 3
Model answer: The claim is partly correct because most metals are shiny and conduct electricity, so shine + conducting often points to a metal. However, the claim is not complete: graphite (a form of carbon) is dark-shiny and conducts electricity but is still a non-metal because it is brittle and most other forms of carbon don't conduct. Galena (a lead-sulfur compound) is metallic-looking but brittle and a poor conductor, it isn't even an element. So we need more than two properties, malleability, ductility, full conductivity and position on the periodic table, to call something a metal.