To beat: to hit with great force, generally using a blunt object
To pat: a light tapping with the whole palm of your hand, but it can be extended to searching people (such as giving a pat down).
To slap: a "hard" tapping, using your palm, and usually with much energy
To flap: something that is loose and moves freely up and down or in the wind, yet touches the surface of something, and this is usually because it is not well attached (like wings--a bird's wings flap).