Thomson's cathode ray particle is now known as the:

1. Thomson's idea was controversial at the time but gradually accepted. 2. His cathode ray particle is what we now call an electron. 3. It is a negatively charged, subatomic particle with a mass more than one thousand times less than that of an atom. 4. Protons and neutrons were identified later and sit in the nucleus. _Source: OpenStax Chemistry 2e (CC BY 4.0), Ch 2 'Atoms, Molecules, and Ions', sections 2.1-2.6_