Everything is made of particles and these particles have electrical charges – they can be positive, negative, or neutral. Atoms can be thought of as the basic building blocks of everything in the universe. They have three components: electrons, protons, and neutrons. Electrons have a negative electric charge and we usually associate these particles with electricity. Protons have a positive electric charge, and neutrons are neutral which means they have no electric charge. Atoms normally have the same number of protons and electrons. The negative charge of the electron cancels out the positive charge of the proton giving the atom a zero net (or neutral) charge. Atoms with an electric charge are called ions. These ions either have more protons than electrons and so have a positive charge or have more electrons than protons and have a negative charge.
The protons and neutrons are glued together in what is called the nucleus (center part) of the atom. The electrons are rapidly moving around outside of the nucleus kind of like a swarm of bees (the hive would be the nucleus). However, the bees in reality would be a long way from the hive. In fact, if the hive (nucleus) were the size of a basket ball, the bees (representing the electrons) would be swarming around the outside as far as a mile away. In other words, the electrons take up almost all of the space of an atom. The next closest nucleus would be a mile away. The nuclei of atoms are locked inside the atom and are not free to travel to other atoms. However, the swarming electrons are free to move. In fact they are freer to move in some substances than others.
Electrons may travel from one material to another just by contact. This is because some materials have a greater “like” for electrons and will “steal” electrons from materials with a lesser “like” for electrons. For instance, a plastic spoon has a greater “like” for electrons than cotton. When rubbed together, the plastic spoon will attract and steal electrons from the cotton. This means the spoon has a greater number of electrons than protons making it have a negative charge. Since the cotton lost some electrons, it is now positively charged (since it now has more protons than electrons). Saran Wrap has even a greater like for electrons than plastic spoons. When rubbed together, the Saran Wrap “steals” electrons from the spoon making the spoon positive. However, only so many electrons can be “stolen” because the substance becomes more positive from losing electrons and holds on to its remaining electrons even harder. If two materials have the same electric charge they will “not like” or repel each other (push each other away). If they have opposite charges, they will “like” each other causing them to be attracted so they come together.
A neutral object, one with equal numbers of protons and electrons, can also appear to be and behave as if it is charged, by having its charges rearranged. This is called charge by induction. This can happen in materials that are poor conductors of electric charges, such as foam, when they are close to highly charged objects. For example if you bring a highly negatively charged object, such as a plastic spoon near a neutral poor conductor, such as a foam peanut, the positive charges in that peanut will collect on the end nearest to the spoon, because the positive charges in the peanut are attracted to the negative charges in the spoon. The foam peanut is now charged by induction, even though overall it is still neutral (has no charge).