Metals, non-metals and their oxides

Most elements are metals. Metals and non-metals behave differently, and so do their oxides.

Practise this lesson free (7 questions)

Comparing properties

Most elements are metals, on the left and in the middle of the periodic table.
PropertyMetals (usually)Non-metals (usually)
AppearanceShinyDull
Conduct heat and electricityGood conductorsPoor conductors (insulators)
Solid shapeMalleable (can be hammered into shape) and ductile (drawn into wires)Brittle
Melting pointMostly highMostly low; many are gases at room temperature
Sound when hitSonorous (ring)Not sonorous

Exceptions

Mercury is a metal but is a liquid at room temperature.
Graphite, a form of the non-metal carbon, conducts electricity.
Only a few metals are magnetic: iron, nickel and cobalt.
So we decide using several properties, not just one.

Oxides: acid or alkali?

Elements burn in oxygen to make oxides.
magnesium + oxygen → magnesium oxide. Magnesium oxide in water with universal indicator turns it blue or purple: metal oxides are bases, and soluble ones make alkalis.
sulfur + oxygen → sulfur dioxide. Sulfur dioxide dissolves in water to make an acidic solution (red or orange with universal indicator). Non-metal oxides that dissolve make acids, for example in acid rain.
Worked example

2.4 g of magnesium burns to make 4.0 g of magnesium oxide. What mass of oxygen joined with the magnesium?

  1. Mass is conserved.
  2. Oxygen = mass of oxide − mass of magnesium
  3. 4.0 − 2.4

Answer: 1.6 g

Key idea

Metals: shiny, conductors, malleable, ductile, sonorous, mostly high melting points. Non-metals: dull, insulators, brittle, low melting points. Metal oxides are bases (soluble ones make alkalis); non-metal oxides make acids.

Key words
Water
Pure water melts at 0 °C and boils at 100 °C. Its density is 1 g/cm³. Ice is less dense than water, so it floats.
Acid
A substance with a pH below 7. Acids turn universal indicator red, orange or yellow and turn blue litmus red.

All KS3 Science key terms and definitions →

Common mistakes
Quick check

Try two quick questions

See if it has sunk in. Answers are marked straight away.

Extra practice

2 more questions

Try each one, then tap to check.

  1. An element is dull, brittle and does not conduct electricity. What is it most likely to be?

    1. A metal
    2. A non-metal
    3. Mercury
    4. An alloy
    Show the answer

    Answer: A non-metal

    Non-metals are usually dull and brittle.

  2. Why is graphite unusual for a non-metal?

    1. It is shiny and magnetic
    2. It is a gas
    3. It is a metal
    4. It conducts electricity
    Show the answer

    Answer: It conducts electricity

    Graphite has free electrons.

Check you have got it

Answer 7 quick questions with instant marking. If you get one wrong, GCSE-ready shows you why and gives you another go. It is free, and you do not need an account.

Practise this lesson free (7 questions)All KS3 Science lessons

Video for this lesson coming soon. Subscribe on YouTube

Sources and references

Checked by the GCSE-ready editorial team, 17 October 2026. Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.

Related lessons