Atoms can join together in groups called molecules. A water molecule has two hydrogen atoms and one oxygen atom. Carbon dioxide has one carbon and two oxygen atoms. Count the atoms in a whole group, not just the colours. A molecule is one group even when it contains several atoms.
Matter and chemistry · Discover & try
How do atoms make different molecules?
Reading level 1 of 5 · EarlyChange
Word help
molecule
A bonded group of atoms.
formula
Symbols showing which atoms and how many are present.
Watch · Try · Explain
See how it works
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Selected composition-and-bond models only; colours, sticks and sizes are symbolic, not chemical synthesis instructions.
What to look for
- Counts differ between molecules
- Bonded atoms remain their elements
- One molecule can contain several atoms
Explain what you noticed
A new molecule has 1 nitrogen atom joined to 3 hydrogen atoms. How many atoms are in the group?
Keep this idea: Count atoms within each bonded group; a group and an atom are different things.
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Source material checked 2026-10-28. Explanations and activities by Nepedia. Source links do not imply endorsement.
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