Course 7.1Lesson 1 of 3

Physical properties of metals

Metals are usually shiny, hard, malleable, ductile and sonorous, and they conduct heat and electricity. Gold and silver are the most malleable and ductile, and silver and copper are the best conductors. There are exceptions, such as mercury, which is a liquid, and sodium, which is soft.

about 25 min1 simulation2 practice questions

Lesson 1 of 3Show all lessons

Try the code and the simulations beside the lesson.

Two kinds of element

Of the elements that we know, about $90$ are metals, about $22$ are non-metals, and a few are in between. Iron, copper, aluminium, gold and sodium are metals. Carbon, sulphur, oxygen and chlorine are non-metals.

We can tell most metals apart from non-metals by their physical properties.

The first twenty elements drawn in the shape of the periodic table. Metals are blue: lithium, beryllium, sodium, magnesium, aluminium, potassium and calcium. Metalloids are green: boron and silicon. Non-metals are orange: hydrogen, helium, carbon, nitrogen, oxygen, fluorine, neon, phosphorus, sulphur, chlorine and argon.

The physical properties of metals

Lustre. A clean metal surface is shiny. This is metallic lustre. Over time, many metals lose it, because they tarnish.

Hardness. Most metals are hard. Iron, copper and aluminium are hard. But some are soft: sodium, potassium and lithium can be cut with a knife.

Malleability. Metals can be beaten into thin sheets with a hammer. This is malleability. Gold and silver are the most malleable. Aluminium is beaten into the foil that we use to wrap food.

Ductility. Metals can be drawn into wires. This is ductility. Gold is the most ductile: a single gram can be drawn into a wire about $2\ \text{km}$ long.

Conduction. Metals are good conductors of heat and electricity. Silver is the best, and copper is next. That is why wires are made of copper and aluminium, and pans are made of copper, steel or aluminium. Lead and mercury are poor conductors for metals.

Sonority. Metals make a ringing sound when they are struck. They are sonorous. School bells and musical instruments are made of metal.

Melting point and density. Most metals have high melting points and high densities. Gold melts at about $1337\ \text{K}$ .

You should find that only lithium, sodium and potassium, with densities below $1\ \text{g/cm}^3$ , float.

The exceptions among metals

Mercury is a liquid at room temperature. Gallium and caesium melt just above room temperature. Gallium melts in your hand.
Sodium, potassium and lithium are soft, have low melting points, and have such low densities that they float on water.
Lead and mercury conduct heat poorly.

Practise with new numbers

Try it in Python

This program lists the densities of some metals, and it says which float on water.

Remember these

Metals are shiny, hard, malleable, ductile, sonorous, and they conduct heat and electricity well.
Gold and silver are the most malleable and ductile. Silver and copper are the best conductors.
Exceptions: mercury is a liquid, sodium is soft, and lithium, sodium and potassium float on water.