Metals conduct, bend, shine and melt at high temperatures. Every one of those properties comes out of the same picture — positive ions in a sea of delocalised electrons. Learn to argue from that model and you can explain any of them.
📚 What you need to know
Malleable (hammered into sheets) and ductile (drawn into wires) because the layers of ions can slide.
Good electrical conductors in the solid and liquid states, because the delocalised electrons can move.
Good thermal conductors, because both the vibrating ions and the moving electrons carry energy.
High melting and boiling points because the electrostatic attraction is strong.
Strong, hard, shiny (lustrous) and sonorous.
A metal is chosen for a job by matching its properties to what the job needs.
Malleability and ductility
Malleable means it can be hammered into sheets. Ductile means it can be pulled into wires. Both come from the same thing: the metal ions are arranged in layers, and a force can make one layer slide over another.
The key point is what happens during the slide. The delocalised electrons are not attached to any particular ion, so they simply move along with them. The attraction between ions and electrons is never broken, so the metal changes shape without falling apart.
The top two layers have shifted to the right. Because every ion has the same charge and the electrons travel with them, nothing repels and nothing breaks.
Compare this with an ionic solid. There, sliding a layer brings like charges next to each other, they repel, and the crystal shatters. In a metal every ion has the same charge and the electron glue moves with them — so metals bend where ionic solids crack. That contrast is a favourite exam question.
Electrical conductivity
To conduct electricity you need charged particles that can move. A metal has them ready-made: the delocalised electrons. Connect a metal to a power supply and those electrons are repelled from the negative terminal and drift towards the positive terminal, carrying charge through the metal.
This is why metals are so different from ionic compounds. An ionic solid has to be melted or dissolved before its ions can move. A metal conducts as a solid, because nothing has to break for the electrons to travel.
The ions stay put; only the electrons move. That is why a solid metal conducts while a solid ionic compound cannot.
💡 Conductivity increases across a period
The more outer electrons an atom gives up, the more delocalised electrons there are to carry charge.
Na gives 1, Mg gives 2, Al gives 3.
So electrical conductivity increases from sodium to aluminium.
Thermal conductivity
Metals also carry heat extremely well, and there are two reasons working together:
The ions vibrate. Heating one end makes the ions there vibrate more, and they knock into their neighbours, passing kinetic energy along the lattice.
The electrons travel. The delocalised electrons pick up kinetic energy at the hot end and carry it rapidly to the cool end, because they can move right through the metal.
The second mechanism is much faster than the first, which is why metals feel cold to touch — they are pulling heat out of your hand very efficiently.
Melting point, strength and hardness
Melting a metal means overcoming the attraction between the ions and the electron sea. That attraction is strong and acts in all directions, so a lot of energy is needed — hence the high melting and boiling points.
The same attraction plus the close packing of the ions is what makes metals strong and hard. And because the attraction gets stronger with more delocalised electrons, higher ionic charge and smaller ions, the melting point rises across a period. That trend is the subject of the next set of notes.
The other properties worth knowing
Property
What it means
Why
Lustre
Shiny when polished
Delocalised electrons reflect light
Sonority
Rings when struck
The lattice vibrates without breaking
Density
Usually high
Ions are packed very closely together
Strength-to-weight ratio
Strong for its mass
Matters for aircraft and vehicles
Corrosion resistance
Resists reacting with air or water
Depends on reactivity and any oxide layer
Toxicity
Whether it is safe for contact
Critical for food, water pipes and implants
Choosing a metal for a job
Exam questions on uses are really “match the property to the requirement” questions. Look at what the object has to do, then pick the properties that matter:
Use
Metal
Properties that matter
Electrical wiring
Copper
Excellent electrical conductor; ductile so it can be drawn into thin wire
Food and drink cans
Aluminium
Non-toxic, resists corrosion by acidic foods, low density, malleable
Cutlery
Stainless steel
Strong, hard, resists corrosion, non-toxic
Saucepans
Aluminium or copper base
High thermal conductivity, high melting point
Aircraft bodies
Aluminium alloys
High strength-to-weight ratio, corrosion resistant
WORKED EXAMPLE
Explain why magnesium can be bent into shape but magnesium oxide shatters when hit.
Magnesium is metallic — layers of Mg²⁺ ions in a sea of electronsWhen layers slide, the delocalised electrons move with them.the attraction is maintained, so it bendsMgO is ionic — alternating Mg²⁺ and O²⁻ ionsSliding a layer brings ions of the SAME charge next to each other.strong repulsion splits the crystal → it shatters
WORKED EXAMPLE
Suggest why copper rather than aluminium is used for household electrical wiring, even though aluminium is cheaper and lighter.
Copper is a better electrical conductor than aluminiumLess energy is wasted as heat in the wires.Copper is very ductile, so it can be drawn into thin flexible wireCopper also resists corrosion wellthe better conductivity outweighs the extra cost and mass indoorsAluminium IS used for overhead power lines, where low mass matters more.
⚠️ Common mix-up
Metals conduct with electrons; ionic compounds conduct with ions. Never swap these two.
Metals conduct as solids. They do not need melting — that’s ionic compounds.
When explaining malleability, say the layers slideand that the electrons move with them. Half the answer only gets half the marks.
Malleable and ductile are not the same word. Sheets versus wires.
For “suggest a use” questions, always link back to a named property. “Because it’s a good metal” scores nothing.
Up next: s-Block and p-Block Elements — why not all metallic bonds are equally strong, and how melting points change across a period and down a group.
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