ACCT 2220 Study Guide - Final Guide: Allophane, Colloid, Clay Minerals

• School: University of Guelph
• Department: Accounting
• Course: ACCT 2220
• Professor: Adeel Mahmood

Document Summary

Soil colloids are very small particles with electrically charged surfaces. Due to their small size, a given amount of colloidal material will have a very large amount of surface area. Soils throughout the world contain different types of colloids, but the ones of most significance in. Canadian soils are layered silicate clays and organic matter (humus) the crystal structure of the layer silicates often results in particles that are charged due to isomorphous substitution and edge charges. The charges on the particles are satisfied by the attraction of oppositely charged ions to the particle surface. Some examples of layer silicate clays are kaolinite, vermiculite, smectite and fine grained mica (illite) and chlorite. These layer silicate clays consist of layers of silicon tetrahedral and aluminium/magnesium octahedral sheets. There are 2 main groups: the 1:1 silicate clays and the 2:1 silicate clays. The 1:1 clays are non-expanding (do not shrink and swell) and have relatively low surface area and low charge.