According to Mr. Dufay, negatively charged atoms will "repel" & positively charged atoms will "attract."
I think you misunderstood a little bit. What he said was: "...rubbed amber repelled objects that rubbed glass attracted." In other words,
if an object is attracted to rubbed glass,
then it will be repelled by rubbed amber. Similarly, if an object is repelled by rubbed glass, then it will be attracted to rubbed amber.
Negatively charged objects repel each other.
Positively charged objects repel each other.
Negatively charged objects attract positively charged objects and vice versa.
Or more simply:
Opposite charges attract each other.
Like charges repel each other.
Who's to say who gets more of what? You see, the way I'm reading this is that when you rub amber, it will become negatively charged...
But, why can't amber become positively charged when you rub it?...
What is it that "says" who gets the excess & who loses?
You can read about that here:
https://en.wikipedia.org/wiki/Triboelectric_effect
Now why on earth would a charged atom (negative or positive) be attracted to a neutrally charged particle?
That's an interesting question, and it's something that's easy to demonstrate. e.g. If you give a plastic comb a negative charge by rubbing it on your clothes, then you can pick up small pieces of paper with it, even though the paper is neutral.
Here's how I understand it:
The neutral object (in this case paper) contains positive charges (protons) and negative charges (electrons).
When the negatively charged comb is brought close to the paper, the electrons in the paper will be repelled and pushed
slightly further away, while the protons will be attracted and pulled
slightly closer.
Now, because the paper's protons are closer to the comb than it's electrons, the attracting force between the comb and the paper's protons is greater than the repelling force between the comb and the paper's electrons. So the net result is attraction between comb and paper.
Notice I said "slightly" above. The electrons and protons in the paper are still part of the same atoms, so they can't move far.
The author who wrote my school textbook should be kicked in the face for stating "nature arranges itself to be neutrally charged" WITHOUT clarifying that nature ISN'T neutral by default, but rather it "wants" to be.
That's not quite fair, the book says:
"Nature arranges itself in such a way where charges always
want to balance."