CHEM 1301 Chapter Notes - Chapter 8.5: Unic, Chemical Formula, Umber

• School: University of Manitoba
• Department: Chemistry
• Course: CHEM 1301
• Professor: Sarrah Vakili

Document Summary

We can visualize metal cations as spheres stak together with the least waste of space. The strong intermolecalur forces in solid crystals can be justified by close packing of sphered. The number of nearest neighbours of each atom or ion is called a coordination number. The packing efficiency is the percentage of volume in the unit cell occupied by particels. The higher the coordination number, the more efficiently the particles are packed together. Packing of spheres is less efficient if we line up rows and coloumns. Close-packing maximizes intermolecular attractions or molecules is minimizes. The second layer atoms can sit directly over the atoms in the first called an aa pattern. Or the second layer can sit over the holes in the first- called an ab pattern (more efficient) There are two alternatives for the third layer: the third layer atoms are placed directly above the atoms in the first layer, duplicating the first layer and forming ababab arrangement.