How is it possible for an atom to have no charge even though is made up up of protons, neutrons, and electrons?
Well, to a first approximation ALL matter is neutral.......
And if all nuclear cores are composed of neutrons and protons, massive particles OF WHICH THE PROTON has a positive charge, there must be an equal number of negative charges supplied by the electrons; that is there must be an equal number of electrons to protons.
As a matter of interest, when J. J. Thompson first discovered the electron, he assigned it a negative charge. This assignment was purely arbitrary. Because now there are more quantum chemists than particle physicists, it would have made lot more sense to assign the electron a POSITIVE charge, and the proton a negative charge.
The point is that the signs are opposite. When you do quantum mechanical calculations with many electron systems, often you get the right numerical answer BUT the wrong sign, simply because you counted the number of electrons odd when it should have been even, or vice versa; all too easy to do.
If an atom has the same number of protons and neutrons, it will have a neutral charge, i.e. no charge at all...
An example would be carbon-12. It has
What about neutrons then? Well, neutrons carry no charge at all, so the total charge will still be