Flashcards
Structure and Properties
Flashcards do conjunto (24)
- 1why do simple molecules not conduct electricity?the molecules do not have an overall electric charge
- 2why do giant ionic lattices have high melting and boiling points?large amounts of energy are needed to break the many strong bonds
- 3what are alloys and what are the differences between the structure of an alloy and a pure metal?materials made from 2 or more types of metals. The different sized atoms of the metals distort the layers in the structure making it more difficult for them to slide over one another
- 4what is special about shape memory alloys? give an examplethey can return to their original shape after being deformed eg) Nitinol used in dental braces
- 5what do the properties of polymers depend upon?what they are made from and the conditions under which they were made
- 6why are Low density and High density polythene different?they were produced using different catalysts and reaction conditions
- 7what are plastics that have individual tangled polymer chains?thermosoftening
- 8what are the properties of thermosetting plastics?they consist of polymer chains with crosslinks betwen them so they do not melt when they are heated
- 9why do thermosoftening polymers melt easily?the chains of polymers are held together by weak intermolecular forces. The forces between the chains are really easy to overcome so its easy to melt the plastic
- 10what size of structure does nano science refer to ?structures that are 1-100nanometers
- 11why may nano-particles have different properties to the same materials in bulk?they have a higher surface area to volume ratio
- 12when can ionic compounds conduct electricity and why?when molten or dissolved in water because the ions are free to move and carry the current
- 13in diamond, how many bonds does each carbon atom form, what type of bond?each carbon atom forms 4 covalent bonds in a giant structure
- 14in graphite, each carbon atom bonds to how may others?each carbon atom covalently bonds to three others forming layers
- 15why can graphite conduct heat and electricity?like metals, graphite has delocalised electrons which can carry current
- 16how strong are the forces between the layers in graphite and what property does this give graphite?the intermolecular forces between the layers are weak and the layers slide over each other because there are no covalent bonds between the layers so graphite is soft and slippery
- 17what can carbon also form with different numbers of carbon atoms?fullerenes
- 18what are the uses of fullerenes? (4)-drug delivery into the body
-lubricants
-catalysts
-in nanotubes for reinforcing materials - 19why can metals conduct heat and electricity?the delocalised electrons in their structure carry charge and move throughout the material
- 20why can metals be bent and shaped?the layers of atoms in metals are able to slide over one another
- 21Do substances that consist of simple molecules have low or high melting/boiling points?low
- 22do substances that have simple molecules have weak or strong inter molecular forces?weak
- 23incomparision to intermolecular forces, are the covalent bonds strong or weakstrong
- 24which forces are overcome when a simple molecular substance melts or boils?the intermolecular forces.. the covalent bonds are still intact
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- gcse chemistry FlashCards sobre Structure and Properties, criado por Ella Wolf em 15-05-2013.
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- Ella Wolf
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