Why doesn't a chemical reaction occur with the movement of electrons in the context of electricity? In school it is generally taught that the movement of electrons between two atoms causes a chemical reaction. However, when it comes to electricity why doesn't a chemical reaction occur with the movement of electrons? (I understand that there is a chemical reaction in a battery, but even with situations like static electricity making your hair stand up, there doesn't appear to be any chemical reaction taking place. Why is the latter situation any different than an atom losing electrons during a chemical reaction?)
 A: Chemical reactions occur when a chemical's covalent bonds are broken and new covalent bonds are formed.  This is a different situation than electricity flowing through a conductor.  For common conductors such as copper, there is approximately one "free" electron per atom that can move through the conductor, and this electron is not bound to any one particular atom of copper.  Because of this, an electric field in the conductor causes this electron to move opposite the direction of the electric field, but no covalent bonds are broken or made as this happens.  As a result, no chemical reaction takes place.
A: For a chemical reaction to occur, you must produce a different chemical substance through the process.  With electron flow, metal atoms are losing and gaining electrons at the same rate.  Also, metallic bonded atoms form mixtures (or consist of single elements), rather than compounds.  Arguably, their are transient ions produced, consider charging an electroscope by contact-there are additional, or fewer electrons around some of the atoms some of the time and ionization should be considered to be a chemical change both conceptually and energetically, but what constitutes a chemical change is largely tautological: If it's a chemical change then what you have is a new substance; if what you have is a new substance then it was a chemical change.  On a molar level, and over time, a wire does not become a new substance, though again, IONIZATION IS strictly speaking a chemical change so on the atomic scale moving electrons IS a transient chemical process, similar to dissolving salts at equilibrium.
A: Chemical reactions do indeed occur with electron movement, not in wires but in chemical systems specially designed to collect up the electrons involved and harness their capacity to perform work. Such a device is called an electrochemical cell or a battery and this field of study is called electrochemistry.
In the battery inside a cell phone, for example, chemical reactions take place which transfer electrons from one chemical element or molecule to another. Those reactions are set up in such a way that those electrons are forced to flow through wires from the site of one reaction which liberates them to another site where they are consumed to complete the chemical reaction.
We can then use that electron flow to power our flashlights, computers, cell phones and MP3 players.
