If, in some cataclysm all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of creature, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it) that all things are made of atoms-- little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence there is an enormous amount of information about the world, if just a little imagination and thinking are applied.

Richard Feynman

But more importantly to our current section is where exactly everything is in the atom. In the center of the atom resides the nucleus of the atom made of the protons and neutrons and the electrons which swirl around the nucleus but do it at a great distance (respective to the incredible small size of the atom).

Protons and Electrons are the two portions of the atom which have an electrical charge. Electric charge can be found in two variations: positive (proton) and negative (electron). If particles have the same charge they repel each other but if they have different charges they attract each other. Therefore the electron is attracted to a proton and repelled from another electron.

Because electrons and protons have equal amounts of electric charge, and in most atoms there are an equal amount of protons and electrons, the overall charge of an atom is usually 0. But through various processes atoms can become charged through the loss or gain of an electron.

This is the first rule of charge when dealing with atoms: in normal circumstances it is always the electron that leaves or comes to the atom. The protons and neutrons are just stuck in that nucleus and cant get out. Atoms which lose or gain an electron are called "ions." This name is given to all atoms with a positive or negative charge but there are special names for atoms with a positive charge, or cations, and with a negative charge, or anions.

you got that?

Electricity is all about electrons moving. Lets say you have an atom, lets make it hydrogen, with only one proton and one electron. Now first thing, electrons are negative, right? And protons are positive? Well for right now I want you to think of each as having a value of 1 (a proton has a +1, an electron -1). So when you have one of each what do you have in terms of charge?? Nothing ditto... one plus negative one is nothing right?? [1+ (-1) =0]

So now back to the hydrogen atom. One proton and one electron (still thinking zero charge?). Well not lets say the electrons gets fed up with the protons and decides to dump him for something better (seems the proton thinks everything should revolve around him). The electron leaves and the proton is left alone.. What happened??

Now before you do anything add the numbers up... (this one is easy) one proton (thing +1) with no electrons (think 0) is +1 and the grand total is 1. This being a positive number leave the atom (well the one proton) with a positive charge.

I know this is simple but it so freaking important and so freaking simple that to get it wrong would be criminal. Plus with this simple method you can figure out if any atom is positive or negative.