1. Explain the principal bonding mechanisms that are most important to all soil mineral structures. Are there other mechanisms that impart stability to specific kinds of minerals? If so, what are they and what are the minerals involved? (Give specific examples.)
2. Employ Pauling’s bond valence principle to show that the residual charge on an O^2. ion bound to Si4 in tetrahedral coordination can be satisfied by two Al^3+ atoms in octahedral coordination or by three Mg^2+ atoms in octahedral coordination. Discuss briefly how this relates to the existence of dioctahedral and trioctahedral sheets in layer silicates.