Middle school3/3 lessons
Atoms and molecules
From the simplified atomic model to molecules: matter is made of organized grains. Chemical symbols and first formulas.
- 01
The simplified atomic model
Nucleus, electrons, neutral atom. Why an atom is defined by its atomic number. The 118 elements of the table.
9 min - 02
Atoms, molecules, ions
When an atom bonds to another, it forms a molecule. When it loses or gains an electron, it becomes an ion. First examples.
8 min - 03
Chemical symbols and formulas
Reading H₂O, CO₂, NaCl. Building a formula from a compound's composition. Subscripts and coefficients.
7 min