If you have a positive electrical force, and a negative electrical force, what do you expect will happen?

I expect that they will add, and their effect at every location will be the sum of their individual effects at that location.

For example:

If they're acting at the same point and in opposite directions, the effect will be the same as a single force at that point, with strength equal to their difference, and in the direction corresponding to whichever one is stronger.

where are the vectors ?

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.