Describe and explain how electrical conductivity occurs in mercury bromide and mercury, in both solid and molten states.

HgBr2 conducts when molten because there are mobile ions in molten HgBr which allows flow of current when an electrical potential difference is introduced to the HgBr in molten state

However HgBr2 does not conduct in the solid state as the ions are fixed in the solid HgBr2 lattice structure

Mercury, which is a metal in its natural form conducts both in the solid and molten states as the delocalized electrons are able to move both in the solid and molten mercury states and as such current flows through mercury when there is an electrical potential difference placed across it

Explanation:

Electricity or electric current flow is the term used to describe the state of movement or flow of matter that carries an electrical charge

It is the steady movement of or flow of electrons. The moving electrons transfer electrical charge round an electrical circuit. In metals, there are freely shared electrons between individual atoms so as to efficiently conduct electricity and so when an electrical potential difference is placed across a piece of metallic object an electron is readily displaced by another electron entering from one end and exiting from the other end of the electrical potential difference