Solid Structures

Solid Structures

Crystal Structures

Ionic, Covalent and Metallic

In ionic halides, oppositely charged ions pack around one in order to increase the bonding energy by maximising electrostatic attraction and minimising repulsion. Each cation is surrounded by 6/8 ions and vice versa. The numbers depend on the relative sizes of the anion to cation. The cyrstal co-ordination numbers are 8:8 in CsCl and 6:6 in NaCl. (You must know both CsCl and NaCl)

In diamond the tetrahedral strong covalent arrangement and 3D giant structure shoud be shown. In graphite, layers of covalent hexagons are held together by weak forces, allowing the layers to slide over each other. 

In solid iodine there is strong covalent bonds which hold the iodine atoms togther in the I2 molecule, and there are weak intermolecular forces holding the I2 units together in the molecular crystal. 

In ice, hydrogen bonds which are between water molecules hold them together in a open tetrahedral structure while the strong bonds within the water molecules are polar covalent.

Metals

Atoms of metallic elements each donate one or more electrons to…