2 O rel. Speed of beam is a fraction of the speed of light. Beam deflected by negative electrode. Cathode rays can be produced by a variety of metals. Cathode rays are beams of negatively-charged particles called electrons.
All atoms contain electrons.
Atoms must contain positive charge. The nucleus is made of positively charged particles called protons. The electrons move in a large volume which is mostly empty space. Accounts for a particle scattering experiment, but not mass of atoms. Most of the atom's volume is occupied by electrons.