dental materials

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dental materials
2011-02-03 00:03:35
chapter three solid liquid

week three
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  1. Two categories of bonds are formed between the 2 atoms, what are the strong bonds called? What are the weak bonds called?
    • primary bonds
    • secondary bonds
  2. What makes primary bonds the strong bonds?
    they involve the exchanging or sharing of electrons
  3. What are three types of primary bonds?
    • ionic
    • covalent
    • metallic
  4. In what type of bond does a metal give an electron to an atom that needs extra which causes both atoms to be charged (one + the other -); and because of this charge, there is an attraction between them?
    ionic bond
  5. In what type of bond are materials such as ceramics usually brittle and poor electrical conductors?
  6. What type of bond occurs when two atoms share electrons in their outer shell; creating full shells for both and are very strong?
    covalent bond
  7. What is a good example of a covalent bond?
    diamond; it is hard and has a high melting point
  8. Think tetracucline staining for what kind of bond?
  9. What type of bond have the electron shared among all the atoms in a lattice formation?
    metallic bond
  10. What type of bond has an electron cloud that causes good thermal and electrical conductivity?
  11. What type of bonds are weak, do not share or transfer electrons leading to deformation or fracture?
    secondary bonds
  12. What are 2 types of secondary bonds?
    • hydrogen
    • van der Vaals
  13. What are the three basic forms that the physical structure of a material may take on?
    • solid
    • liquid
    • gas
  14. What are 5 things that affects material classification?
    • physical structure
    • application
    • manipulation
    • composition
    • reaction
  15. What form has shape and volume?
  16. what form has volume but no shape?
  17. What form has neither shape or volume?
  18. primary atomic bonds hold ______ together, giving them strength and stability; the most stable have a regular crystalline structure with molecules in a regularaly spaced pattern
  19. If molecules in a solid are arranged in a random form with no regular pattern, the solid is less stable and called what?
  20. What 7 characteristics are used to describe solids?
    • density
    • hardness
    • elasticity
    • stiffness
    • ductility
    • malleability
    • brittleness
  21. What is the densest tooth structure? What is the densest restorative material?
    • enamel
    • gold
  22. ________ is used to define a material's resistance to wear and abrasion
  23. What are two of the hardest materials?
    • enamel
    • porcelain
  24. If deformation is not permanent and the material recovers from the force completely, it has good what?
  25. What is the stiffness of a material measured by?
    young's elastic modulus
  26. Stiffer materials have a _________ modulus
  27. materials with poor ductility are classified as what?
  28. _______ is brittle and cannot undergo much tensile stress without fracture; its ultimate strength is about equal to its elastic limit
  29. gold is very _______ and _________; it is easily compressed and formed into a thin sheet
    • ductile
    • malleable
  30. The combination of malleability and ductility gives a metal the ability to resist fracture or abrasion even at fine margins, giving the metal what?
    edge strength
  31. In most cases, _______ tend to be ductile and malleable, but _______ are brittle
    • metals
    • ceramics
  32. The study of flow of liquids is the science of what?
  33. The higher the viscosity, the _______ is a liquid's ability to resist flow
  34. value of viscosity depend on the nature of the fluid; thin fluids have _____ viscosity and thicker fluids have ____ viscosity
    • low
    • high
  35. usually the viscosity of liquids ________ as the temperature increases
  36. liquids that flow more easily under mechanical forces, fluoride gels are often advertised as this kind of liquid
    thixotropic material