CHM120H5 Chapter Notes - Chapter 16: Enthalpy, X-Ray, Silt
Document Summary
Changes of state occur due to changes ___ the molecule. Molecules have a slightly positive end and a slightly negative end. When the positive and negative ends are close to each other and attract. The molecules are too far apart therefore they become weakerespecially in low pressure gases. A hydrogen bond is a very strong dipole dipole attraction. Occurs between a hydrogen and a highly electronegative atom: nitrogen oxygen fluorine. Large and strong h-x hydrogen bonding: large electronegative values of the lightest elements: which makes it very polar, the small size of the elements: more close to the hydrogen so it further strengthens the bond. Since it takes a lot of energy to break the bonds the boiling point is very high. For these weak forces to become strong enough to produce a solid the movement of particles must be greatly reduced. As the mass increases -> the number of electrons increases -> the number of temporary dipoles increases.
