Since I don't know what "these" refers to here, I will just assume that the question addresses social networks generally.
Some impacts are:
Positive -better information -security (you can mark people safe during Earthquake) -faster contact with peopl -possibility of forming groups -additional communication platform
Negative:
-less privacy -lack of control over data -being able to spy on people -being able to find things from the past -bosses spying on their workers
