CHEM101 Study Guide - Ionic Radius, Lone Pair, Intermolecular Force

• School: University of Alberta
• Department: Chemistry
• Course: CHEM101
• Professor: Yoram Apelblat

Document Summary

Forces that hold molecules together in the condensed phases. Attraction between the charge of the ion and an opposite dipole. Solvation of ionic compounds in a polar solvent (often water). Na+ + x h2o [na(h2o)x]+ (aq) + energy x will vary from ion to ion. Arrange na+, cs+ and mg2+ in order of solvation energy. Ionic radius effect smaller radius stronger force. Molecules will orient to maximize +ve and ve attractions, or minimize like charge repulsion. Attraction by mg is strongest b/c of greater charge and smaller ionic radius (see previous example for na+ vs. Same charge, but na+ is smaller than cs+ (higher in the periodic table). E (mg2+) > e (na+) > e (cs+) Dipole diploe forces become weaker as distance increases. Dipole dipole interaction not important in gases as molecules are far apart. Ordering that results from dipole orientation can cause a substance to persist as a solid or liquid at temperatures higher than expected.