This video covers how atoms and ions are arranged in mineral structures. I go over crystal structures, coordination numbers, types of coordination polyhedron (linear, trigonal, tetrahedral, octahedral, cubic, hexagonal closest packing), how Pauling's rules affect crystal structure (Pauling's rules: the electrostatic valency principle, sharing of polyhedral elements 1 & 2, and the principle of parsimony), covalent vs. ionic vs. metallic vs. van der waals bonds, and ionic substitution / solid solution. The atomic radius of cations and anions that come together to form minerals determines the overal mineral structure. This is because the size of an ion controls how many closest neighbors or neighboring ions it can bond to, aka: its coordination number. The larger the central ion, the higher the coordination number. So how are atoms arranged in minerals? Molecules can be arranged as linear, trigonal planar, square planar, tetrahedral, trigonal bipyramidal, octahedral, cubic, or closest packing polyhedra. These individual coordination polyhedra are repeated throughout the mineral structure giving the mineral a macrostructure or crysal habit dependent on its atomic structure. However, molecular coordination polyhedra can repeat in different ways, for example, silica is a tetrahedral molecule, but silica tetrahedra can be repeated and arranged in a mineral in various ways: typically as chains, sheets, or framework structures. Sheet silicates include minerals such as mica which is why mica minerals are so platy and flaky. Quartz is an example of a framework silicate structure, which is why quartz is so hard and durable. But how are these polyhedra repeated? What types of bonds hold molecules together in minerals? Types of bonds in minerals include covalent, ionic, metallic, & van der waals bonds. Salt is an example of a mineral with ionic bonds, diamond is an example of a mineral with covalent bonds, gold is an example of a mineral with metallic bonds, and graphite is an example of a mineral with van der waals forces. However, minerals can contain multiple types of bonds, for example, ice contains both covalent bonds and hydrogen bonds, which are van der waals bonds. Lastly, I discuss substitution of ions into mineral structures by replacement or insertion into interstitial sites or vacancy sites between ions. Hope you enjoy! ;) Reference: Chapter 4 in Earth Materials by Cornelis Klein: https://amzn.to/3mnQqcb GEO GIRL Website: https://www.geogirlscience.com/ (visit my website to see all my courses, shop merch, learn more about me, and donate to support the channel if you'd like!) 0:00 Common ions in minerals 2:20 how ion size affects mineral structure 4:43 Atomic arrangements (coordination polyhedra) 8:49 Coordination number & polyhedra practice! 9:43 Silicate structures 11:15 Paulings rules 11:51 The coordination principle 13:45 The electrostatic valency principle 16:13 Sharing polyhedral elements I 17:01 Sharing polyhedral elements II 18:14 The principle of parsimony 19:05 Forces that hold crystals together 21:44 Chemical bond types 24:32 Atomic substitution or solid solution 28:21 Upcoming content! 29:04 Bloopers! Directly offset your carbon footprint with Wren: https://shrsl.com/3d0t2 Tools I use as a geologist/teacher/student: Geology field notebook: https://amzn.to/3lb6dJf Geology rock hammer: https://amzn.to/3DZw8MA Geological hand lens: https://amzn.to/3jXysM5 Camera: https://amzn.to/3l6fGRT Carbon-neutral backpack: https://shrsl.com/3cvkc Disclaimer: Links in this description may be affiliate links. If you purchase a product with these links I may receive a small commission, but there is no additional charge to you! Thank you for supporting my channel!