Movement of electrons in conductors and insulators In conductors, the electrons can easily move unlike in insulators that prevent them from moving. What properties in conductors and insulators make them act in such way? Is it related to the position of electrons? Or there is another reason? Thanks for helping
 A: In conductors the electrons are loosely bound whereas in case of insulators, this is not true.
The concept comes from what is known as Band theory in metals. 
When atoms come together to form a compound, their atom orbital energies mix to form molecular orbital energies. As more atoms begin to mix and more molecular orbitals are formed, it is expected that many of these energy levels will start to be very close to, or even completely degenerate, in energy. These energy levels are then said to form bands of energy.
The valence band is the band of energy where all of the valence electrons reside and are involved in the highest energy molecular orbital.
The conduction band is the band of energy where positive or negative mobile charge carriers exist. 
According to the band theory, metals will actually act as insulators at absolute zero. Above this temperature and yet still staying below the melting point of the solid, the metal would act as a semiconductor.Semiconductors are classified by the fully occupied valence band and unoccupied conduction band. With the small band gap in between these two bands, it takes a certain amount of energy to excite the electrons from the valence to conduction band.As stated previously, continuous bands of energy are formed due to the combinations of molecular orbitals close in energy. Of course, due to the mass amounts of different molecular orbital mixings, bands of varying energy will form. The difference between these band energies is known as the band gap.

In insulators, the electrons in the valence band are separated by a large gap from the conduction band, in conductors like metals the valence band overlaps the conduction band, and in semiconductors there is a small enough gap between the valence and conduction bands that thermal or other excitations can bridge the gap. 
You can also consult from this pdf if you want added information or details.
A: Metallic elements are elements on the left side of the periodic table, elements which have outer shells with a low number of free electrons in their outer shell. The free electrons can easily detach themselves from the atom. Metals naturally tend to form crystals containing free electrons.
