Electrical Conductivity How and Why

To conduct electricity you need: Charged particles that are free to move Electrons and ions are charged particles If the electrons and ions are free to move around, the substance can conduct electricity

Metals You learned that a property of metals are that they conduct electricity Metals conduct electricity because they have mobile electrons which are electrons that can move from atom to atom. The mobile electrons carry the electrical current. http://www.drkstreet.com/resources/metallic-bonding-animation.swf

Ionic Compounds Ionic compounds are formed when a metal and a nonmetal form a chemical bond. For example NaCl (salt) is an ionic compound. Which one is the metal and which one is the nonmetal? The Na ion has a +1 charge and the Cl ion has a -1 charge. They are charged particles. When the ionic compound is in the solid phase, the ions are stuck in place.

Ionic Compounds (Cont.) When the ions are stuck in place, they cannot conduct electricity. When the ionic compound is melted it becomes a liquid. In the liquid phase the ions are free to move. When the ionic compound is dissolved in water (aq), the water separates the ions from each other and the ions are free to move. In these two situations, ionic compounds conduct electricity.

Acids and Bases The formulas of acids and bases often contain only nonmetals. If a compound only contains nonmetals, it is bonded covalently. Covalent compounds typically do NOT conduct electricity—even in liquid or aqueous form. For example, sucrose (C12H22O11) will not form charged particles when dissolved in water. The C12H22O11 stays together. Acids and Bases are special. When they are mixed with water, they break up into ions. For example, hydrochloric acid (HCl) breaks up into H+ ions and Cl- ions.