Starter

In pairs :-1. Build; water, carbon dioxide, Ammonia

2. Draw these molecules in 3D, include bon dangles and lone pairs.

Must : Describe Van der Waals, Dipole, and Hydrogen Bonding.

Should : Relate intermolecular force to physical property.

Could : Imagine 3D shapes of molecules.

What are Intermolecular Forces ?

• Attractive forces between neighbouring molecules.....

Van der Waal’s Forces

• ALL intermolecular forces are Van der Waal’s forces...

• Temporary fluctuating dipoles.

Dipole ForcesDipole-Dipole interactions result when two polar molecules approach each other in space. When this occurs, the partially negative portion of one of the polar molecules is attracted to the partially positive portion of the second polar molecule.

Hydrogen BondingA hydrogen bond is the electromagnetic attractive interaction between polar molecules in which hydrogen is bound to a highly electronegative atom, such as nitrogen, oxygen or fluorine.

Why did we do this experiment ?

• Type of IMF determines many things, one of which is solubility.

• I2(aq) + I−(aq) I⇌ 3−(aq)

• In which solvent was Iodine most soluble ?• How did the introduction of a polar Iodide

affect the result ?

5 Question Quiz

• Which would have the higher boiling point ? – Chlorine, or Hydrogen Chloride – Why ?

• Why is water a liquid ?• Why won’t Sodium Chloride dissolve in

Decane ?• What is another name for Van der Waals

forces ?• What is Darth Vader’s dad called ?

Homework

• Use Mr Midgley site here.

• Chem factsheet on bonding issued yesterday.