When we rub a ballon against a sweater why does the electrons move from the sweater to the ballon and not the protons?

• Inside an atom the protons and neutrons are held firmly at the very center in a structure called the nucleus of the atom.
• The electrons however are held much more loosely in the orbitals around the nucleus of the atom.
• Some electrons can be found at the surface, and if the surface is rubbed, they can be rubbed away.
• Therefore, when you rub a balloon on your sweater some of the electrons are transferred from the sweater to the balloon. The sweater becomes positively charged.