Term
What are the 3 phases of materials and how do they differ? |
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Definition
Gas, liquid, solid weak-strong attraction between molecules |
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Term
what is long and short range order? |
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Definition
Short range(Liquid) – spatial relationship between atoms 5-10 neighbors apart
Long range(solid) – spatial relationship of molecules repeated millions of times
**gases have no order** |
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Term
What is an example of long range order? Short range? |
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Definition
Crystalline – long range Amorphous – short range |
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Term
What is an ionic bond and what is an example of it? |
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Definition
ionic bond is where one molecule gives an electron to another molecule, EX: table salt |
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Term
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Definition
two molecules sharing electrons |
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Term
What is an example of a covalent bond? |
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Definition
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Term
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Definition
Valence electrons are shared by all the atoms that make up the object |
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Term
What is: Positive cores surrounded by a cloud of negative mobile valence electrons. |
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Definition
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Term
What is an example of a metallic bond? |
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Definition
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Term
What are secondary bonds? |
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Definition
Partial charges from an uneven distribution of electrons around an atom or molecule |
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Term
What is another name for a secondary bond? |
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Definition
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Term
What are secondary bonds important in determining? |
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Definition
the properties of polymers |
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Term
What is a permanent dipole? What do these result in? |
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Definition
one atom has permanent positive charge and one has negative charge – result in weak bonds |
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Term
What is a fluctuating dipole? |
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Definition
uneven distribution of electrons around atoms resulting in weak bond |
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Term
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Definition
special permanent dipole, only one electron and when pulled away hydrogen nucleus left partially unshielded, strong dipole results |
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Term
How do the atomic bonds of metals allow them to be ductile? |
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Definition
Electron cloud allows atoms to slide past each other with little difference |
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Term
Explain how the ionic bonds of ceramics make this material strong but brittle. |
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Definition
Atoms slide past each other encounter an atom with same charge – repulsion (brittle when pulled apart) strong when compressed |
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Term
Why are ceramics suited to replace lost tissue structure? |
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Definition
Translucent and comes in many colors/shades |
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Term
What is the atomic structure of polymers like? |
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Definition
Long chains of covalently bonded, repeating units |
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Term
What are polymers used for in dentistry? |
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Definition
Mouthguards, bleaching tray, dental instruments, composite filling material |
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Term
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Definition
mixture of ceramic and polymer |
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Term
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Definition
suspensions of one material in another (impression material & fluoride foam) |
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Term
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Definition
2 liquids that do not blend together to form one liquid (transformation from liquid to a gel) |
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