A laminar boundary layer is a layer

Intermolecular forces:force of attraction between covalent molecules,much weaker than covalent bonds within the molecules.DIAMOND:form of pure carbon.Each acrbon atom has four electrons in its outer shell and it therefore formss four civalent bonds.In diamond,each carbon bonds strongly to four other carbon atoms in a tetrahedal arrangement.Diamond has a a very high melting and boiling point.This is because of the very strong carbon-carbon covalent bonds,which extend throughout the whole crystal in three dimensions.A lot of energy has to be supplied to break these strong covalent bonds.All substances with giant covalent structures are solids with high melting and boling points because a lot of energy has to be supplied to break all the strong covalent bonds throughout the giant structure.Diamond is very hard.Lot of energy has to be supplied to break the strong covalent bonds in the giant structure.Diamond doesn't conduct electricity.All the electrons in the oiter shells of the carbon atoms are tightly held in covalent bonds between the atoms,none are free to move.

Graphite is also a form of carbon.Graphite has a layer structure.Graphite is a soft material.Although the forces holding the atoms together in each layer are very strong,the attractions between the layers are much weaker and not much energy is needed to overcome them.Graphite has high melting and boiling points.To melt graphite,you don't just have to separate the layers,you have to break up the whole structure,including the covalent bonds,needs very large amounts of energy because the covalent bonds are so strong.Graphite conducts electricity.