Simple molecules LO: Describe the properties of substances made from simple molecules. (D) Explain how covalent bonds are strong, but simple molecules have low melting points. (C) Explain why simple molecules have particular properties (B) Explain the differences in properties of simple molecules which occurs even though covalent bonding is strong (A/A*)

Make these models Carbon Hydrogen HCl H2O Oxygen CH4 C2H6 Chlorine CO2 Single bond Double bond HCl H2O CH4 C2H6 CO2 CH3CH2OH

Covalent compounds Water Sulphur Ethanol What do these substances have that is similar ? What tests for properties could you do ? Iodine

Covalent bonds are stronger than ionic bonds…..FACT !

Practical Using a boiling tube and a thermometer find out… The temperature that the wax melts at. The temperature that the water boils at. Record your results. WEAR GOGGLES STAND UP REPORT ALL SPILLS AND BREAKAGES

Conductivity demo Wax Ethanol Ammonia Say why covalent molecules do not conduct electricity

Covalent compounds do not conduct electricity because…. There are no electrical charges to carry the electricity

Melting and Boiling I said that covalent bonds are stronger than ionic. If this is the case why do many covalent compounds have very low melting and boiling points ?

Covalent bonds are strong, but each molecule is separate to its neighbour. The forces between each MOLECULE is very small. There are weak intermolecular forces.

Make a statement About covalent bonding. The rest of the class will have to decide if it is true or false.

Write a Question About anything to do with chemistry that we have done so far.

Simple ____________ do not conduct _____________ because there are no __________ on the molecule. They have very weak ___________ between molecules and are usually found as ___________ or gases. When they do form ____________ they are __________ and not __________. They do not dissolve in ____________ but can ___________ in other liquids. forces hard charges solids dissolve water molecules liquids electricity waxy