The Solid State
How do the salt crystals (left) from salt shaker and the larger crystals (right) compare to the atomic structure of NaCl below? How would you describe the arrangement of ions in NaCl?
How are the chloride ions arranged around the sodium ions or the sodium ions around the choride ions?
sodium ion at center chloride ion at center
Each ion is octahedrally surrounded by the other ion in a very orderly or repeated fashion. Hence NaCl is a crystalline solid.
Now view the structures of the two crystalline forms of carbon. What is the hybridization of carbon in each structure?
Which structure is more dense? View in the spacefill mode and look at the packing of the atom carbons form all sides.
The carbon in diamond is tetrahedral (sp3) and trigonal planar in graphite (sp2).
The p orbital on the sp2 carbons in graphite allow for the electrical conductivity. The sheets, held together by induced dipole interactions, allow for the layer to slip.
What about the packing of ions in an ionic solid like LiI or CsCl?
Now view the structure of fullerine, C60. Does the fullerine structure resemble diamond or graphite? Why? Describe the ring structure in fullerine?
Examine the structure of ice or solid water given below. Does the structure resemble diamond or graphite? Ice floats in liquid water. View the structure in spacefill and explain why.
Each water molecule is tetrahedrally bound by hydrogen bonding to four other water molecules. The structure is somewhat open making it less dense that its liquid.
Try your skills on these solids:
What is the force of attraction in solid carbon dioxide, dry ice?