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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
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What makes primary bonds the strong bonds?
they involve the exchanging or sharing of electrons
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What are three types of primary bonds?
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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
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In what type of bond are materials such as ceramics usually brittle and poor electrical conductors?
ionic
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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
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What is a good example of a covalent bond?
diamond; it is hard and has a high melting point
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Think tetracucline staining for what kind of bond?
covalent
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What type of bond have the electron shared among all the atoms in a lattice formation?
metallic bond
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What type of bond has an electron cloud that causes good thermal and electrical conductivity?
metallic
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What type of bonds are weak, do not share or transfer electrons leading to deformation or fracture?
secondary bonds
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What are 2 types of secondary bonds?
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What are the three basic forms that the physical structure of a material may take on?
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What are 5 things that affects material classification?
- physical structure
- application
- manipulation
- composition
- reaction
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What form has shape and volume?
solid
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what form has volume but no shape?
liquid
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What form has neither shape or volume?
gas
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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
solids
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If molecules in a solid are arranged in a random form with no regular pattern, the solid is less stable and called what?
amorphous
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What 7 characteristics are used to describe solids?
- density
- hardness
- elasticity
- stiffness
- ductility
- malleability
- brittleness
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What is the densest tooth structure? What is the densest restorative material?
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________ is used to define a material's resistance to wear and abrasion
hardness
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What are two of the hardest materials?
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If deformation is not permanent and the material recovers from the force completely, it has good what?
elasticity
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What is the stiffness of a material measured by?
young's elastic modulus
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Stiffer materials have a _________ modulus
higher
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materials with poor ductility are classified as what?
brittle
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_______ is brittle and cannot undergo much tensile stress without fracture; its ultimate strength is about equal to its elastic limit
porcelain
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gold is very _______ and _________; it is easily compressed and formed into a thin sheet
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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
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In most cases, _______ tend to be ductile and malleable, but _______ are brittle
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The study of flow of liquids is the science of what?
rheology
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The higher the viscosity, the _______ is a liquid's ability to resist flow
greater
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value of viscosity depend on the nature of the fluid; thin fluids have _____ viscosity and thicker fluids have ____ viscosity
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usually the viscosity of liquids ________ as the temperature increases
decreases
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liquids that flow more easily under mechanical forces, fluoride gels are often advertised as this kind of liquid
thixotropic material
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