.Definite sharp melting points ·Symmetry -X-ray diffraction by crystals 7.1.2 The lattice and unit cell ·Lattice: A periodic pattern of points in space,such that each lattice point has identical surroundings. 。 Can be reproduced by translational motion along the vector between any two points.• Symmetry •Definite sharp melting points •X-ray diffraction by crystals t T 7.1.2 The lattice and unit cell • Lattice: • A periodic pattern of points in space, such that each lattice point has identical surroundings. • Can be reproduced by translational motion along the vector between any two points