Niels Bohr changed the model of the atom.
What did Bohr add to the model?
The positive charge is concentrated in a small nucleus.
Electrons orbit the nucleus in shells at fixed distances.
Atoms are tiny solid spheres that cannot be divided into smaller parts.
The nucleus contains neutral particles called neutrons.
51 exam-style questions on OCR GCSE Chemistry 1.2 Atomic structure, covering 1.2.1 Development of the atomic model, 1.2.2 The nuclear model and the size of atoms, and 1.2.3 Subatomic particles in atoms and ions. Each one has a worked solution and a mark scheme showing where the marks go.