01:160:161 Lecture Notes - Lecture 2: Packing Density, Coordination Number, Trigonal Planar Molecular Geometry
Document Summary
Solids divided into two broad categories a. b. Crystalline solids: generally have a well-defined shape because particles occur in an orderly arrangement i. Amorphous solids: have poorly defined shapes because particles do not show long-range order. Crystalline solids are orderly geometric structures whose lattice points are occupied by atoms, ions, or molecules i. Study of solid structure is often done using the technique of x-ray diffraction crystallography b. Crystal lattice: arrangement of the particles in a crystalline solid i. Unit cell: smallest unit that shows pattern of arrangement for all particles. Three dimensional, usually containing two or three layers of particles. Repeated over and over to give the macroscopic crystal structure of the solid. Starting anywhere within the crystal results in the same unit cell. Coordination number: number of other particles that each particle is in contact a) b) Ions: number of oppositely charged ions with which an ion is in contact.
