《演示文稿专业英语》-(课件).pptVIP

Dispersion Forces  The on one atom are attracted to the on a neighbouring atom. This creates an “ ” (i.e. （=id est） temporary) dipole on the first atom. The instantaneous dipole on the first atom then induces an instantaneous dipole on the second atom. The two induced dipoles attract each other. For example, the consist of , non-polar atoms…… Surface Tension A molecule in the liquid is stabilized by the attraction of the other liquid molecules. A molecule on the surface will be at a higher energy than one in the bulk of the liquid. ?Surface tension is a measure of the strength of intermolecular attractions which pull on molecules at the surface of a liquid. Surface Tension ?It is because of its high surface tension that water tends to “ ”up on a surface. That’s because a gives the minimum ratio of surface area to volume. The high surface tension of water also causes molecules on the surface to pack very closely together. This is why some insects can “walk on water”. Thank you! Unit cell ?The unit cells stacked in 3-D space describe the bulk arrangement of atoms of the crystal. The unit cell is given by its lattice parameters：the length of the cell edges the angles between them. while the positions of the atoms inside a unit cell are described by the set of atomic positions measured from a lattice point. Molecular Solids Lattice points occupied by molecules held by intermolecular forces Fairly soft, moderately low melting point (usually 200oC), poor thermal and electrical conductivity Examples: Argon , CH4, CO2, H2O The majority of common and oxides are coordination polymers.  Thank you! * * Gas, Liquid and Solid Chapter 12 气体，液体和固体 Gas, Liquid and Solid high temperatures low tempera