<span>It is the valence orbit that controls the electrical properties of the atom. The valence electron is referred to as a "free electron.' Valence electrons have the highest energy of all electrons in an atom; they are also the most reactive, meaning they are usually the electrons involved in bonding. When silicon atoms combine to form a solid, they arrange themselves into an orderly pattern called a crystal.</span>
The medium of a wave is any substance that carries the wave, or through which the wave travels.Ocean waves are carried by water, sound waves are carried by air, and. the seismic waves of an earthquake are carried by rock and soil.