intermolecular forces

• how do polar solvents dissolve in water ?

  An example is sodium chloride , water molecules attract the sodium positive ions and the chlorine negative ions.Sodium is attracted to the oxygen and the chlorine is attracted to the hydrogen
• what are inter molecular forces

  forces of weak interactions between dipoles of molecules
• what is the strength of the inter molecular forces using > to indicate ?

  single covalent > hydrogen > permanent dipole interactions > london forces
• what are london forces

  weak forces that exist between all molecules and act between induced dipole in different molecules
• what is an induced dipole ?

  electrons are constantly moving

  so it produces a changing dipole in a molecule,

  at any instant an instantaneous dipole will exist and then induce a dipole onto neighboring molecule.

  The induced dipole will then induce further neighboring molecules
• how are the strength of induced dipole interactions measured ?

  the more electrons in each molecule

  the larger the instantaneous and induced dipoles

  the greater the induced dipole dipole interaction

  the stronger the attractive forces between molecules
• what is a permanent dipole dipole interaction ?

  interactions between permanent dipoles in different polar molecules
• why does hydrogen chloride have a higher boiling point then fluorine ?

  fluorine molecules are non polar and so they only have LONDON forces

  hydrogen chloride are polar and have London AND permanent dipole dipole interactions between molecules

  extra energy is needed to break the additional permanent dipole dipole interactions between hydrogen chloride molecules so therefore it has a higher boiling point
• whats hydrogen bonding ?

  a type of permanent dipole interaction founding between hydrogen atoms attached to an electronegative atom like oxygen nitrogen and fluorine
• where do hydrogen bonds act between

  a lone pair of electrons on a electronegative atom in one molecule and a hydrogen atoms of a different molecule

  its the strongest type of inter molecular interactions
• draw the diagram for hydrogen bonding between 2 water molecules


  here

  
• what is the anomalous behaviour of water

  solid ice is less dense then liquid water
• why does solid ice float on water ?

  hydrogen bonds hold water molecules apart in an open lattice structure

  the water molecules in ice are futher apart than in water

  so its less dense and floats on water
• why does water have a relatively high melting and boiling point

  water has London forces and hydrogen bonding so a large amount of energy is required to break the hydrogen bonds in water

  the lattice breaks the rigid arrangement of hydrogen bonds in ice is broken and when water boils the hydrogen bonds break completely