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Unit Cell

lattice point. A ___________________________ solid possesses rigid and long-range order. In a crystalline solid, atoms, molecules or ions occupy specific (predictable) positions.

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Unit Cell

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  1. lattice point A ___________________________ solid possesses rigid and long-range order. In a crystalline solid, atoms, molecules or ions occupy specific (predictable) positions. An ____________________________solid does not possess a well-defined arrangement and long-range molecular order. A _____________________________________ is the basic repeating structural unit of a crystalline solid. • At lattice points: • Atoms • Molecules • Ions Unit cells in 3 dimensions Unit Cell

  2. Objectives Today • Solids/Crystal Structures • Unit Cell • Cubic Unit Cells • Types of Solids • Lattice Energy from Born-Haber Cycle • Logger Pro Intro Lab

  3. lattice point A crystalline solid possesses rigid and long-range order. In a crystalline solid, atoms, molecules or ions occupy specific (predictable) positions. An amorphoussolid does not possess a well-defined arrangement and long-range molecular order. A unit cell is the basic repeating structural unit of a crystalline solid. • At lattice points: • Atoms • Molecules • Ions Unit cells in 3 dimensions Unit Cell

  4. Shared by 2 unit cells Shared by 8 unit cells

  5. 4 atoms/unit cell 2 atoms/unit cell 1 atom/unit cell (8 x 1/8 + 6 x 1/2 = 4) (8 x 1/8 + 1 = 2) (8 x 1/8 = 1)

  6. d = d = m m V V x = x 1 mole Ag 107.9 g 7.17 x 10-22 g 6.022 x 1023 atoms mole Ag 6.83 x 10-23 cm3 When silver crystallizes, it forms face-centered cubic cells. The unit cell edge length is 408.7 pm. Calculate the density of silver. V = a3 = (408.7 pm)3 = __________________ ___ atoms/unit cell in a face-centered cubic cell m = 4 Ag atoms = ___________ = ___________________

  7. Extra distance = 2d sinq = nl BC + CD = (Bragg Equation)

  8. 1 x 154 pm = 2 x sin14.17 nl 2sinq X rays of wavelength 0.154 nm are diffracted from a crystal at an angle of 14.170. Assuming that n = 1, what is the distance (in pm) between layers in the crystal? nl = 2d sin q n = 1 q = 14.170 l = 0.154 nm = 154 pm = ____________ d =

  9. Types of Solids • ________________ Solids • Lattice points occupied by cations and anions • Held together by electrostatic attraction • Hard, brittle, high melting point • Poor conductor of heat and electricity CsCl ZnS CaF2

  10. Types of Solids • Ionic Crystals or Solids • Lattice points occupied by cations and anions • Held together by electrostatic attraction • Hard, brittle, high melting point • Poor conductor of heat and electricity CsCl ZnS CaF2

  11. Types of Solids • Solids • Lattice points occupied by molecules • Held together by intermolecular forces • Soft, low melting point • Poor conductor of heat and electricity

  12. Types of Solids • Molecular Crystals or Solids • Lattice points occupied by molecules • Held together by intermolecular forces • Soft, low melting point • Poor conductor of heat and electricity

  13. carbon atoms Types of Solids • _________________ Solids • Lattice points occupied by atoms • Held together by covalent bonds • Hard, high melting point • Poor conductor of heat and electricity graphite diamond

  14. carbon atoms Types of Solids • Network or covalent Crystals or Solids • Lattice points occupied by atoms • Held together by covalent bonds • Hard, high melting point • Poor conductor of heat and electricity graphite diamond

  15. nucleus & inner shell e- mobile “sea” of e- Types of Solids • _________________ Solids • Lattice points occupied by metal atoms • Held together by metallic bond • Soft to hard, low to high melting point • Good conductor of heat and electricity Cross Section of a Metallic Crystal

  16. nucleus & inner shell e- mobile “sea” of e- Types of Solids • Metallic Crystals or Solids • Lattice points occupied by metal atoms • Held together by metallic bond • Soft to hard, low to high melting point • Good conductor of heat and electricity Cross Section of a Metallic Crystal

  17. Types of Crystals Types of Crystals and General Properties

  18. An ____________________________solid does not possess a well-defined arrangement and long-range molecular order. A _______ is an optically transparent fusion product of inorganic materials that has cooled to a rigid state without crystallizing Non-crystalline quartz glass Crystalline quartz (SiO2)

  19. An amorphoussolid does not possess a well-defined arrangement and long-range molecular order. A glass is an optically transparent fusion product of inorganic materials that has cooled to a rigid state without crystallizing Non-crystalline quartz glass Crystalline quartz (SiO2)

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