8. Crystal chemistry Table of contents 8.1 Dense and other crystal packings 8.2 Crystallization 8.3 Crystal habits 8.4 Coordination and geometry of polyhedra 8.5 Largest crystals 8.6 Specific crystal structures 8.7 Geometrical problems 8.1 Dense and other crystal packings Questions & answers π What is meant by close paking in crystals? π If spheres of radius r are arranged in CCP fashion (ABCABC), what will be the vertical distance between any two consecutive A layer? π We have 2 tetrahedral voids at each body diagonal. Is this true only for FCC and HCP unit cells? π What are tetrahedral voids in FCC with an example of NaCl? π In terms of lattice parameter, what is the closest distance between two atoms in BCC and FCC arrangement? π A substance AxBy crystallizes in a face centred cubic (FCC) lattice in which atoms A occupy each corner of the cube and atoms B occupy the centre of each face of the cube.The correct composition of the substance AxBy is ? Can it be specified? 8.2 Crystallization Questions & answers π How are hydrated crystals formed? π What is the theory of making rock sugar crystals? π Do all minerals have crystal structures? Why or why not? π Are all crystals less dense comparred with their liquid state like ice is comparred to water? π How do mineral crystals and sapphire crystals compare and contrast? π What is the crystalline phase? π How do crystals form? π What is a βcrystal defectβ? π Which material is ferrite made of? π What is crystalline? π What is an ionic and crystal bond? What is the difference between metallic and crystal bonds? 8.3 Crystal habits Questions & answers π How are ice crystals formed in a cloud? π What is the origin of macroscopic crystal faces? π What crystal system do ice crystals belong to? π What are the different kinds of snow crystals? How do they compare and contrast? π Why are diamond and feldspar crystals octahedral in form? π How do pyrite crystals achieve their shape? π Are there any crystal structures of ice other than the hexagonal form? π When a snowflake forms, how do the six arms grow to be so similar to each other? π Are there no two snow crystals alike? π Is ice considered a crystal, and does that make water a liquid crystal? π What shape is a salt crystal? π What gives crystals their "crystalline" shapes? Is it their crystalline structure of atoms? Does a crystalline structure always produce crystal shaped substances? 8.4 Coordination and geometry of polyhedra Questions & answers π Metals pack in different crystal structures such as FCC, BCC and so on. So what is the reason for them to pack in one form not the other? π What is the vacant space in a BC lattice unit cell? π How do I find the number of the next nearest neighbours in a simple cubic lattice? π Why is the coordination number for a face-centered cubic unit cell 12 and not 14? π Is ClF3 trigonal bipyramidal? π What is the number of the nearest neighbors for a given lattice point in FCC lattice? π What is the difference between Platonic solids and Archimedean solids? π If five edges of a tetrahedron have the same length 4, what is the maximum volume of the tetrahedron? π What is the shape of a distorted tetrahedron? π What are the possible deformations of the cube and their corresponding symmetries? π Is there a platonic structure that can contain 360 spheres close packed? π What are the properties of a Platonic solid? 8.5 Largest crystals Questions & answers π How big and how heavy is the largest quartz crystal found in nature? π What crystals can grow the largest in nature? π How big is the worldβs largest crystal? 8.6 Specific crystal structures Questions & answers π What is the structure of NaOH? Is it a typical ionic crystal? π What is meant by alpha, beta, gamma, and delta phases in crystallography? π What is the lattice constant of NaCl crystal? The molecular weight of NaCl is 58.44 and the density is 2.167g cmΒ³. π Silver crystallizes in a face-centred cubic lattice (FCC). What is the lattice parameters of silver? π Is the structure of XeF4 a square bipyramidal? π Is XeF4 square planar? π How many formula units are in one unit cell of barium hexaferrite? π What is the shape of XeO3? π How do you produce the chemical formula of a compound crystallized in a cubic lattice (solid state chemistry, crystallography)? π Cs chloride crystallises in cubic unit cell with cl ions in corner and CS ions in the centre of cube how many CsCl molecules are there in unit cell? π What is the structure of C60? π Is there any way to determine the type of crystal by its chemical formula? Which is trigonal crystal, CaSO4.2H2O, NaNO3, or MgSO4? π How do I find the bonding angle in crystallographic orthorhombic- βΊ sulphur (s8) in 3d (look at the link for images)? π How is TiO2 arranged in anatase, rutile, and brookite structures? π Do halite and diamonds have the same crystal shape/structure? π This picture shows the cubic unit cell for zns. how many zn2+ ions are in this cubic unit cell? π What is the crystal formula of peridot? 8.7 Geometrical problems Questions & answers π What is meant by drawing a standard 001 projection or 011 projection of a cubic crystal? π Is the golden ratio seen in bismuth crystals? π What is the angle between directions [111] and [121] of a cubic crystal?
