Sorting matter by properties
Every element can be classified as a metal, a non-metal, or (in a few special cases) a metalloid. We don't decide this by guessing — we look at measurable physical properties: how the element looks, how it conducts heat and electricity, and how it behaves when you try to bend, hammer or heat it.
Physical property: a characteristic of a substance that can be observed or measured without changing what the substance actually is — for example colour, hardness, or the ability to conduct electricity.
Properties of metals
- Lustrous (shiny): metals have a shine when polished or freshly cut.
- Good conductors of both heat and electricity — electrons move freely through them.
- Malleable: they can be hammered or rolled into thin sheets without breaking (think aluminium foil).
- Ductile: they can be drawn out into thin wires (think copper wiring).
- High melting points (generally) — most metals stay solid at room temperature, mercury being the famous exception.
- Sonorous: they make a clear ringing sound when struck — this is why bells are made of metal.
- High density — metals generally feel heavy for their size.
Properties of non-metals
- Dull appearance — no metallic shine (with the exception of iodine and graphite, which do have a slight lustre).
- Poor conductors of heat and electricity — most are good insulators. Graphite (a form of carbon) is a notable exception that conducts electricity.
- Brittle when solid — they shatter or crack rather than bending into shape.
- Generally lower melting and boiling points — many non-metals are gases at room temperature (oxygen, nitrogen, chlorine).
- Low density compared to metals, generally.
- Not sonorous — they produce a dull thud rather than a ring when struck.
Remember: these are general trends, not absolute rules. Science is full of interesting exceptions — that's part of what makes the periodic table fascinating to study.
Metals and non-metals on the periodic table
The periodic table is arranged so that elements with similar properties fall into predictable regions:
| Region | Where found | Examples |
|---|
| Metals | Left and centre of the table (the majority of all elements) | Iron (Fe), Copper (Cu), Gold (Au), Aluminium (Al), Sodium (Na) |
| Non-metals | Upper right-hand corner | Oxygen (O), Carbon (C), Sulfur (S), Chlorine (Cl), Nitrogen (N) |
| Metalloids | Along the zigzag "staircase" line dividing metals from non-metals | Silicon (Si), Boron (B), Germanium (Ge) |
Interesting extra: metalloids show properties of BOTH metals and non-metals. Silicon, for example, looks shiny like a metal but is a semiconductor (poor conductor unless treated) — this is exactly why it's used in computer chips!
Everyday uses of metals
- Copper — used for electrical wiring because it is an excellent conductor of electricity and is also ductile enough to be drawn into thin wires.
- Aluminium — used for foil and drink cans because it is light in weight, malleable, and resists corrosion (it forms a protective oxide layer).
- Iron and steel — used in construction (bridges, buildings, reinforcing rods) because of their strength and high melting point.
- Gold — used in jewellery because it is lustrous and does not tarnish or corrode.
Everyday uses of non-metals
- Oxygen — essential for respiration in living organisms and for combustion (burning).
- Carbon — found in many forms: graphite (pencil "lead" and electrodes), diamond (cutting tools and jewellery), and as the basis of all organic compounds in living things.
- Sulfur — used to manufacture fertilisers, matches, and sulfuric acid.
- Chlorine — used to purify and disinfect drinking water and swimming pools by killing harmful microorganisms.
Links forward: In Grade 9, you'll study how metals and non-metals react chemically with oxygen, water and acids, and use the periodic table to predict reactivity trends.