Is it true that opposite charges attract?

Answer 1

Yes, opposite charges (i.e. and positive and negative) attract each other. It is also true that "like" charges (i.e. two negative charges or two positive charges) repel one another.

At the molecular level this can be explained by thinking about electrons. Electrons are small negatively charged particles within an atom. In general, a molecule, particle, or object that has a "negative" charge has a surplus of electrons (i.e. has extra negative charges within it). In contrast, positively charged molecules, particles, or objects have a shortage of electrons (i.e. are missing negative charges). Since a negatively charged object has extra electrons, and a positively charged object is missing them, the two objects will naturally be attracted to one another because they each have something that the other wants. That is, the object with extra electrons wants to find someone to give it's extra electrons to while the object that is missing electrons wants to find someone who has extra ones to give. The opposite is true for "like" charges wanting to repel each other.

I hope this helps!:)