Final answer:
The three main groups of clay minerals are kaolinite, illite, and smectite. Kaolinite has a stable layered structure, while illite contains potassium ions between the layers. Smectite has a complex structure and high water absorption.
Step-by-step explanation:
The three main groups of clay minerals are kaolinite, illite, and smectite.
1. Kaolinite: Kaolinite is a common clay mineral that has a layered structure. It consists of sheets of silicate tetrahedra and aluminum octahedra. The structure of kaolinite is relatively stable.
2. Illite: Illite is another common clay mineral that also has a layered structure. It consists of sheets of silicate tetrahedra and aluminum octahedra, similar to kaolinite. However, illite also contains potassium ions between the layers, which gives it a different structure and stability compared to kaolinite.
3. Smectite: Smectite is a clay mineral with a more complex structure compared to kaolinite and illite. It consists of sheets of silicate tetrahedra and aluminum octahedra, like the other clay minerals. However, smectite also contains water molecules between the layers, which gives it a high degree of water absorption and expansion. This makes it less stable compared to kaolinite and illite.