Atoms and molecules
If you cut something in half again and again, what would you find?
Play
Explain
Everything is made of tiny atoms.
They are too small to see.
Everything around you is made of tiny pieces called atoms. A single drop of water holds more atoms than there are stars in the galaxy.
Atoms can join together to make molecules. A water molecule has two hydrogen atoms and one oxygen atom.
About 90 kinds of atoms occur in nature, and they make everything from ice cream to stars.
An element contains one kind of atom. A compound has two or more kinds of atoms bonded together.
Chemical formulas count the atoms. H₂O has 2 hydrogen and 1 oxygen, and CO₂ has 1 carbon and 2 oxygen.
Atoms are about 10⁻¹⁰ m across. A line of 10 million atoms would be only about 1 mm long.
- Atoms are tiny
- Atoms join up
- Molecules make everything
Want the full story?
The balls in the sim are only a model. Real atoms have no solid edge, and are mostly empty space with a cloud of electrons. Not all substances are molecules: salt is a repeating lattice of ions.
Try it at home
You need modelling clay or playdough.
You need: modelling clay or playdough.
Stick two balls of playdough together.
- Roll one large ball of playdough for oxygen, and two small ones for hydrogen.
- Press them together to make a water molecule.
- Try to make a carbon dioxide molecule.
What's happening: you have built a model. Real molecules have the same pattern, but are billions of times smaller.
Physics is life
Your body
You are made of atoms.
Daily life
Water is made of molecules.
Nature
Trees are made from air and water.
Space
Atoms were made in stars.
Quick check
Question 1 of 3
Words to know
Atom: The tiny building block of everything around you.