why do electrons flow through some solids and not other?

Answer 1

Electrons have to flow for electricity to be conducted.

In some solids, such as ionic compounds (salts), the solid matrix is so rigid and tight that the electrons are trapped and cannot flow.

In some solids, such as metals, the structure is flexible and the electrons a loosely connected and considered mobile. Therefore, electricity can flow through metals.

Answer 2

One class of solids, Conductors, allow the free movement of electrons through their particles. Conductors include metals and water. There is another type, insulators, which disallow the electrons from easily flowing through the particles. They include Wood and Rubber. I believe there is also semi-conductors/semi insulators which are, you guessed it, partly Conductor, or partly Insulator.

It's all how the particles arrange themselves that allow free movement of Electrons or stop it... Hope this helps!

Answer 3

It depends on whether the electrons are tied up in covalent bonds or are free to move and conduct the current. In one form of carbon - a diamond - the electrons are all bound up in the bonds. A diamond will not conduct electricity. In graphite - another form of carbon - there are layers of material with free-moving electrons between the layers. These free-moving electrons will move to carry the current. Graphite will conduct electricity.