Chemical formulas are a compact way to describe atom counts. In H2O, the small 2 belongs to hydrogen, so the group contains two hydrogen atoms and one oxygen. Atoms joined into a molecule are not new elements. Different combinations and arrangements can produce substances with very different properties, even when some atoms are shared.
Matter and chemistry · Discover & try
How do atoms make different molecules?
Reading level 2 of 5 · DevelopingChange
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
The interactive activity is loading.
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.
Follow the sources
Source material checked 2026-10-28. Explanations and activities by Nepedia. Source links do not imply endorsement.
You’ve reached the end of this journey
Choose another journey →