As the conduction electrons are free to move randomly, i.e they are not restricted to a particular atom, then why don't these atoms get positive charge due to loss of these conduction electrons?
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$\begingroup$ Are you asking about a net production of positive ions, or are you asking about if positive ions exist as a transition state? $\endgroup$– NatCommented Aug 27, 2018 at 6:33
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$\begingroup$ looking into semiconductors might help people.eecs.berkeley.edu/~hu/Chenming-Hu_ch1.pdf $\endgroup$– anna vCommented Aug 27, 2018 at 7:03
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$\begingroup$ Who said they don't? A metal can be described as a periodic lattice of positive ions sourounded by the free electrons "gas". But this has nothing to do with electric current. The positive ions are there even in the absence of current. $\endgroup$– nasuCommented Nov 9, 2020 at 13:00
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2 Answers
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You can think of the electron motion in the conductor as being something like this:
So no atom is left without an electron. In effect the conduction electrons hop from atom to atom.
I must emphasise that this isn't really what happens because the conduction electrons are delocalised so they are spread out over distances much larger than the atomic spacing. If you're interested in pursuing this the electron states are approximately described by Block waves. However as the simplified diagram shows, every atom is still on average associated with one of the conduction electrons so on average remains neutral.
answered Aug 27, 2018 at 6:11
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$\begingroup$ thanks for your reply! okay so,lets take a semi conductor.At the junction of it as the electrons from n region leave into p why is there a formation of positive charge if we apply the same concept as above.! $\endgroup$– RohithCommented Aug 27, 2018 at 16:19
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To expand a bit on the previous answer, the behaviour of electrons in a metal is approximated by the Free Electron Model. All metals, that are good conductors, have only one or two valence electrons (i.e. in the outer electron shell). In this model, we imagine that the valence electrons leave the atom and the remaining ions form a regular lattice of some arrangement. The free electrons then form a sea or a gas that is free to move through the crystal. On average, the whole structure remains electrically neutral.
This model is very accurate in representing many of the bulk properties of metals - like density and electrical and thermal conductivity.
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$\begingroup$ thanks for your reply! okay so,lets take a semi conductor.At the junction of it as the electrons from n region leave into p why is there a formation of positive charge if we apply the same concept as above.! $\endgroup$– RohithCommented Aug 27, 2018 at 16:18
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$\begingroup$ The Free Electron Model applies only to metals. Semi-conductors are a whole new ball game! $\endgroup$ Commented Aug 28, 2018 at 5:44