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.