BONDING, STRUCTURES & PROPERTIES CHEMISTRY N4 CHEMISTRY BONDING, STRUCTURES & PROPERTIES CONDUCTIVITY

BONDING, STRUCTURE & PROPERTIES CHEMISTRY N4 CHEMISTRY BONDING, STRUCTURE & PROPERTIES CONDUCTIVITY After completing this topic you should be able to : Write the formula of an element or compound and include the symbol to indicate the state of a substance for a solid, liquid, gas and solution. Carry out an experiment to find out is a substance conducts electricity i.e. is a the substance a conductor or an insulator. Relate the ability to conduct electricity to the type of bonding present in the substance.

CONDUCTIVITY SOLID (s) H2O(s) LIQUID (l) H2O(l) STATE SYMBOLS Testing if a substance conducts electricity provides useful information about the type of bonding in a substance. Whether a substance is a solid, liquid or dissolved in water to form a solution can affect the substance’s conductivity. STATE SYMBOLS When writing a formula you can indicate the state of a substance by writing a state symbol. SOLID (s) H2O(s) LIQUID (l) H2O(l)

GAS (g) H2O(g) SOLUTION (aq) CuSO4 (aq) The Latin word for water is AQUA. This is where the symbol (aq) comes from. The (aq) means aqueous. CuSO4 (aq) Solutions made using water as the solvent are called AQUEOUS SOLUTIONS.

potassium chloride solution solid carbon dioxide (dry ice) liquid oxygen Complete the FORMULAE WITH STATE SYMBOLS examples on page 4 of the Bonding, Structure and Properties Examples Booklet.

CONDUCTION AND SOLIDS (s) The conductivity of a substance can be tested using the following apparatus. battery bulb carbon rods Substance being tested INVESTIGATION : CONDUCTION and SOLIDS Use the conduction testing apparatus to test a number of solids. CONCLUSION : How does the conductivity of a solid relate to the bonding present in the substance? Are there any exceptions to the pattern of conduction and bonding?

CONCLUSION The only solids which conduct electricity are metals and carbon in the form of graphite. The solids which conduct all have metallic bonding EXCEPT carbon (graphite) which has covalent bonding.

CONDUCTION AND LIQUIDS (l) Mercury the metal which is liquid a room temperature. INVESTIGATION : CONDUCTION and LIQUIDS Use the conduction testing apparatus to test a number of liquids. Some solids will be heated until they melt. The conductivity of these liquids will be tested. These solids should be marked with an * on your table of results. CONCLUSION : How does the conductivity of a liquid relate to the bonding present in the substance? What type of bonding is present in most of the substances which are liquid at room temperature?

CONCLUSION The only liquid at room temperature which conducted electricity was mercury. Mercury has metallic bonding. Apart from mercury, all the liquids at room temperature have covalent bonding. The only melted solid which conducted was lead(II) bromide. Lead(II) bromide has ionic bonding.

CONDUCTION AND SOLUTIONS (aq) INVESTIGATION : CONDUCTION and SOLUTIONS Use the conduction testing apparatus to test a number of solutions. CONCLUSION : How does the conductivity of a solution relate to the bonding present in the substance dissolved? CONCLUSION The only solutions which conducted electricity contained an ionic compound.

Conductivity (conductor / insulator?) CONDUCTION SUMMARY Conductivity (conductor / insulator?) Type of Bonding solid (s) liquid (l) solution (aq) metallic conductor conductor ionic insulator conductor conductor covalent insulator insulator insulator Solid conductors have metallic bonding. Carbon in the form of graphite is an EXCEPTION, as it has covalent bonding. Liquid conductors have metallic and ionic bonding. Solutions which conduct contain compounds which have ionic bonding. Covalent substances NEVER conduct electricity EXCEPT carbon (graphite).