Really elementary conceptual question

[Utter Novice]

Hi everyone.

I find myself in an unusual position; my training is in philosophy, specifically linguistic philosophy and philosophical logic. A publisher friend of mine has asked me to edit an introductory physics title from a purely conceptual perspective, my knowledge of physics is almost nil (which was actually the reason for my friend's request).

The problem is that I am unable to find (in the sources which are accessible to me) an explanation for a phenomenon which strikes me as conceptually fundamental.

Here it is:

When two substances rub against each other, usually there is no net transfer of electrons and so neither becomes charged.

However sometimes when two substances rub against each other there is a net transfer of electrons and a charge is created.

The usual example seems to be amber.

The explanation I have come across is that this happens because amber has a high electrical resistance.

But how can that be any kind of explanation?

There would appear to be electron donors and electron gatherers (if I may use those invented terms).

But what is the reason for this?

Why do some substances so easily donate their electrons and others gather the electrons of other substances?

Finally what causes the gathered electrons to stay with the electron gatherer?I presume I have missed some obvious point here and I should be most grateful if someone could help me out.Thanks.

 

[Nienstien]

Simply put:
Some substances hold their electrons closely
Some substances hold their electrons loosely
The reason falls back to the electron arrangements of the compound or element, electrons like to be in discrete shells. If an atom has a full inner shell and 1 valence electron (electrons on the outer most shell are valence electrons) it easily loses that 1 valence electron. If an atom has say 7 out of 8 electrons needed to complete a shell it will easily take a valence electron off of another substance like the one mentioned before.
There is a chart of materials which show which ones are more apt to give electrons and which are more apt to take called the electrostatic series.

 

[Utter Novice]

Thank you very much Neinstein.

Of course now I want to ask two things:

1. Why do electrons like to be in a discrete shell?

2. What determines when a shell is full, is it always when there are eight electrons in it or was that just an example.

Apologies if this is moronic, but I have been utterly unable to find the answers.

 

[Nienstien]

Ill start with your second question because it's a little bit simpler.
The pattern for electron shells is 2, 8, 18, 32, 32, 18, 8 really you only need to know the first 3 or so for basic use because they don't always fill shells before they go into the next. For example element 20 is calcium, it's shells are 2,8,8,2 but number 21, scandium's shells are 2,8,9,2. In addition to the pattern being wacky at times, the shells can also take different shapes (mind you all of this is far from basic physics). Another thing to note is shells are also called energy levels, and there is a reason for this. The farther an electron is from the nucleus the more energy it has, like pulling a spring farther apart, when an electron is ripped away from the nucleus is takes energy. Therefore even full shells can exchange electrons between themselves and it would be very hard to define a full shell, excluding the first 2 because they are very neat in their electron placement.
In fact the only reason I say the pattern is 2,8,18,32,32,18,8 is because that is the farthest element discovered's electron placement.
Now no one really know for sure why electrons stay in discrete shells but that's just what science has shown to happen. On a quantum scale there isn't always an in-between stage. Let's say I was stretching the spring, I could hold the ends close (low energy) or pull them far (high energy) and I could also go in between the two, but when you look at particles it's a lot more choppy in the sense you are either in level 1 or level 2, there is no in between.
Hope it helps.

 

[Utter Novice]

Thanks so much.

 

[Oldfart]

... my knowledge of physics is almost nil (which was actually the reason for my friend's request).

Won't your asking questions like this reduce the value that your friend sees in you? Just a thought...

OF

 

[Utter Novice]

Actually not at all; but I see your point.