Experiments by J. J. Thomson showed that electrons have a negative charge.
They also showed that the mass of an electron is about 1/2000 of the mass of a hydrogen atom.
Atoms have no overall charge.
Which conclusion can be made from this evidence alone?
Most of the atom must be empty space with a nucleus at its centre.
A hydrogen atom must be made of about 2000 electrons joined together.
The electrons in an atom must be arranged in shells around the nucleus.
Most of the mass of an atom must be in the part that is not electrons.
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.