Answer:
Neutrons and Protons
Step-by-step explanation:
The atom is made of 3 particles: electrons, protons and neutron.
The diffuse cloud is made of electrons, that have a negative charge and a smaller mass than the neutrons and protons.
The nucleus is made of neutrons, that have no electric charge, and protons that have a positive charge and repels the electrons. Both neutrons and protons have a bigger mass than the electrons.