intermolecular forces

• london forces are temporary
• london forces act between all atoms and molecules
• london forces

  Electrons keep moving within the atom  

  Where there is a high amount of electrons it becomes partially negative  

  Areas with less electrons become partially positive  

  This means atom can become temporarily attracted to another atom  
• hydrogen bonding

  strongest intermolecular

  Can only occur between F H O
• permanent dipole dipole 


  attractive forces between two neighbouring molecules with a permanent dipole
• intramolecular forces are stronger than intermolecular forces e.g. hydrogen is weaker than covalent bond
• Describe how London forces form between halogen molecules.


  the uneven distribution of electrons causes a temporary dipole in the first molecule which causes a second dipole in another molecule
• Methanol, CH3OH, is miscible with water in all proportions. Sodium chloride is much less soluble in methanol than in water.

  Explain these statements using your knowledge of the interactions between solutes and solvents.

  there is hydrogen bonding between methanol and water

  the strength of all intermolecular forces between methanol and water is approximately the same as those in water and methanol

  in sodium chloride the hydration of Na+ and Cl- happens

  the ionic bonding is stronger than the bonding between sodium chloride ions and water
• Explain why hydrogen bonding causes ice to be less dense than liquid water


  there us more space between molecules duet to 3D lattice

  hydrogen bonds are longer than covalent bonds