This is all related to GCSE content, but it doesn't go into enough depth for it to make sense: When a ballon sticks to a wall after becoming negatively charged, why does the surface of the wall become positively charged? I would assume that the repulsion between negative charges forces the electrons to move, but does this mean that atoms can change their structure? Theoretically, the atom still has the same amount of protons and electrons, so its overall charge is neutral - does this mean that the electrostatic attraction has a very short 'range' and only reaches the surface of an atom? And why is it that the wall that the subatomic particles in the wall move instead of those on the balloon? Is it because charged particles 'stronger' than neutral particles? Another question I have is regarding lightning. Why do the negatively charged ions sink to the bottom of the cloud - electrons are lighter than protons, so shouldn't it be the other way round? Actually (I just now thought of this)but is it because the ice and water have the same chemical formula and therefore the same amount of electrons and protons, which would mean that the negatively charged ones are heavier because they have the same amount of protons, but more electrons? Also, with paint sprayers. I understand why you get an even coat, but what confuses me is the fact that the car becomes charged as well. The car was presumably neutral to begin with, so how exactly do the paint sprayers cause the car's particles to become ions? I am also confused by earthing. I understand that allowing the charge to flow elsewhere will stop it from shocking you, but how does the charge just 'disperse'? My revision guide says that negative ions flow down, and positive ones flow up - if it flows up, wouldn't it just still cause a shock? So if the negative ones flow down, does that mean the earth is positively charged? I thought it had a neutral charge though, so does it flow down because it has a more positive charge than the ions?