Why do ions have charges? - Help.com

By defintion, an atom with a charge is called an ion. They are atoms whose number of electrons do not match the number of protons.

I think has to do with our magnetic field or something.

A neutral atom has no charge. This is because all protons carry 1 unit of positive charge, and all electrons carry one unit of negative charge. Like magnets, these positive and negative charges are what hold an atom together. (There is a third particle in an atom, called a neutral, but they exist simply to give size to the nucleus and have no charge.) When a reaction occurs that causes a neutral atom to lose or gain an electron, it will have a total charge that is unequal to zero (the sum of the negative units and the negative units). For more information on the usual charge for an atom of a particular element (carbon, sulfur, oxygen, magnesium, etc.) you will have to study more about the way the table of elements is constructed and the arrangement of electrons in an atom. Remember, to become an ion in basic chemistry, only electrons are gained and lost. The number of protons, will always tell you what element the atom is.