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Grades 8–10 Intermediate About 15 min Version 1 Awaiting review Premium

Atoms and molecules: build the models

An atom is the smallest particle of an element. A few elements, the noble gases such as helium and neon, exist as single atoms. Most atoms join to others to form molecules. If all the atoms in a molecule are the same, it is a molecule of an element, such as oxygen (O₂). If it contains two or more kinds of atom, it is a molecule of a compound, such as water (H₂O). In a ball-and-stick model, each ball is an atom, its colour shows the element, and each stick is a bond.

What you will learn

  • Build ball-and-stick models of simple molecules.
  • Count the atoms in a molecule from its formula.
  • Distinguish atoms, molecules of elements and molecules of compounds.

Before you start

  • Know the symbols of common elements.

Materials

  • Modelling balls (white hydrogen, red oxygen, black carbon, blue nitrogen, green chlorine, yellow helium, purple neon and argon) and sticks

Equipment

  • Molecular model kit

Procedure

  1. Choose a card and build its model with balls and sticks.
  2. Count how many atoms and how many kinds of atom it has.
  3. Place each card in the right group.