Crystalline

Crystalline

1. REVIEW!!!!! WHAT ARE THE DIFFERENT INTERMOLECULAR FORCES? HOW CAN THESE IMFs AFFECT THE PHYSICAL PROPERTIES OF A SUBSTANCE?

2. WHAT ARE THE DIFFERENT PROPERTIES OF A SOLID? DO SOLIDS HAVE THE SAME MOLECULAR SHAPE AND STRUCTURE?

3. ARE ALL SOLIDS THE SAME??

4. TRY TO FIGURE OUT THE DIFFERENCE BETWEEN THE NEXT TWO SLIDES

5. Crystalline and Amorphous Solids

6. LEARNING OBJECTIVES Students will be able to: Describe the difference in structure of crystalline and amorphous solids. Describe the different types of crystals and their properties: ionic, covalent, molecular, and metallic.

7. ACT IT OUT!!

8. THE CLASS WILL CHOOSE A REPRESENTATIVE. THIS REPRESENTATIVE WILL ACT TO THE CLASS THE WORD THAT I WILL GIVE TO HIM. THE CLASS IS ONLY GIVEN 2 MINUTES TO ACT-OUT THE GIVEN WORD.

9. SOLID CRYTALS DEFINITE SHAPE RANGE GEOMETRY ARRANGEMEMT ATOMS MOLECULES VOLUME NON CRYSTALS

10. The (Common) Phases of M atter “ Condensed Matter ” includes both of these. We’ll focus on Solids ! This doesn’t include Plasmas , or Bose-Einstein condensates but these three are the “ common ” phases!!

11. Gases Gases have atoms or molecules that do not bond to one another in a range of pressure, temperature & volume. Also, t hese molecules have no particular order & they move freely within a container.

12. 16 Similar to gases, L iquids have no atomic or molecular order & they assume the shape of the ir containers. Applying low levels of thermal energy can easily break the existing weak bonds. Liquids

13. Solids consist of atoms or molecules undergoin g thermal motion about their equilibrium position s, which are at fixed point s in space. Solids can be crystalline , or amorphous . Solids (at a given temperature, pressure, volume) have stronger interatomic bonds than liquids. So, Solids require more energy to break the interatomic bond s than liquids . Solids

14. Crystals are Everywhere!

15. More Crystals

16. All crystals are solids, but all solids are not crystalline! Crystals have symmetry and long range order Spheres & small shapes can be packed to produce regular shapes.

17. All Solids! All solids have “resistance” to changes in both shape and volume. Solids can be Crystalline or Amorphous Crystals are solids that consist of a periodic array of atoms, ions, or molecules If this periodicity is preserved over “large” (macroscopic) distances the solid has “Long-range Order” Amorphous solids do not have Long-Range Order , but they often have Short Range Order

18. Solids Crystals : Short-range Order Long-range Order Amorphous solids: ~Short-range Order No Long-range Order

19. Crystalline Solids A Crystalline Solid is the solid form of a substance in which the atoms or molecules are arranged in a definite, repeating pattern in three dimensions. Single C rystals , ideally have a high degree of order , or regular geometric periodicity, throughout the entire volume of the material .

20. Amorphous Solids Amorphous (Non-crystalline) Solids are composed of randomly oriented atoms, ions, or molecules that do not form defined patterns or lattice structures. Amorphous materials have order only within a few atomic or molecular dimensions.

21. Amorphous Solids Amorphous (Non-crystalline) Solids have order only within a few atomic or molecular dimensions. They do not have any long-range order, but they have varying degrees of short-range order. Examples of a morphous material include a morphous silicon, plastics, & glasses.

22. Amorphous (Non-crystalline) Solids have no regular long range order of arrangement of atoms. Some examples from everyday life : 1. Polymers, 2. Ceramics, 3. Window glass, 4. Cotton candy! The two sub-states of amorphous solids are the Rubbery and Glassy states Amorphous Solids

23. Amorphous (Non-crystalline) Solids have no regular long range order of arrangement of atoms. Amorphous Solids can be prepared by rapidly cooling molten material. Rapid cooling minimizes time for the atoms to pack into a more thermodynamically favorable crystalline state. Amorphous Solids

24. Illustration of the continuous random network structure of the atoms in an amorphous solid Amorphous Solids

25. Amorphous materials - Materials, including glasses, that have no long-range order, or crystal structure. Glasses - Solid, non-crystalline materials (typically derived from the molten state) that have only short-range atomic order. Glass-ceramics - A family of materials typically derived from molten inorganic glasses & processed into crystalline materials with very fine grain size & improved mechanical properties. Amorphous Solids

26. Atomic arrangements in crystalline silicon and amorphous silicon. (a) Amorphous silicon. (b) Crystalline silicon. Note the variation in the inter-atomic distance for amorphous silicon.

27. Crystallography Crystallography ≡ B ranch of science that deals with the geometric description of crystals & their internal arrangements. It is the science of crystals & the math used to describe them.

28. Crystallography Crystallography is a VERY OLD field which pre-dates Solid State Physics by about a century! So (unfortunately, in some ways) much of the terminology (& theory notation) of Solid State Physics originated in crystallography.

29. Solid State Physics Started in the early 20 th Century when the fact that Crystals Can Diffract X-rays was discovered. Around that same time the new theory of Quantum Mechanics was being accepted & applied to various problems. Some of the early problems it was applied to were the explanation of observed X-ray diffraction patterns for various crystals & (later) the behavior of electrons in a crystalline solid.

30. Crystal Lattice Crystallography focuses on the geometric properties of crystals. So, we imagine each atom replaced by a mathematical point at it’s equilibrium position. A Crystal Lattice (or a Crystal ) ≡ An idealized description of the geometry of a crystalline material. A Crystal ≡ A 3-dimensional periodic array of atoms. Platinum Platinum S urface ( Scanning Tunneling Microscope)

31. In a 1 whole sheet of paper, you write a 2-3 paragraph reflection about the following: Physical Properties of liquids in relation to the IMF Structure of crystalline and amorphous solids.