An electric charge is either positive or negative. In science we have the electron and the proton, the electron is negative, so I’m going to abbreviate it using a negative sign, (or a subtraction sign) so that’s going to stand for negative—some people would also write it like this.
We also have the proton, which has a positive charge, which I’m going to abbreviate using the addition sign, (that means positive)—this also means positive, if I write it like that. The interaction between electrons and protons is very interesting. If I have two electrons, so that’s an electron right there, (has the negative sign) then I have another electron right here, these two electrons do not want to be near each other, in fact, they want to repel each other away.
I’m going to draw this double arrow right here signifying that the two electrons are going to push away from each other. This is also the case if you have two protons, the protons do not want to get near each other, so those are the two protons pushing away from each other.
Now if you have a proton over here with a positive charge, and an electron over here with a negative charge, they’re going to join together to form an atom because they’re attracted to each other, and they want to become one. Now, it’s interesting to note that large objects do not have electric charges.
Like this whiteboard for example, it’s not positive or negative, but it’s made up of atoms, and atoms contain protons and electrons, which have positive and negative charges. Well, the reason this whiteboard has no electric charge is because the electrons are negative and the protons are positive, and they cancel each other out.
The electric forces cancel each other out, okay, because in an atom you have an equal number of electrons and protons. In an atom say you have 5 electrons; you will have 5 protons; you have 5 negative charges and you have 5 positive charges; so those charges cancel each other out, giving the item no charge.
Since this whiteboard is made up of atoms with no charge, the white board has no charge. Now, if you have more electrons in a substance than protons, it’s going to have a negative charge; if you have more protons than electrons in a substance; it’s going to have a positive charge.
Now, I want to elaborate a little bit more on what I talked about right here. When you have a proton and an electron, say they’re that far apart, the force right here is going to be a lot smaller than if the proton’s right here and the electron’s right here.
When the proton and electron are very close to each other, the force between them is very large—the attractive force that’s bringing them together is very large, a lot bigger than the electric charge up here. One last point is that when a substance or an atom, when an atom has less electrons than protons, it’s called an ion; it’s also called an ion when it has more electrons than protons. Either way, it’s called an ion because there’s an imbalance of protons and electrons.