Structure and Properties

Ella Wolf
Flashcards by Ella Wolf, updated more than 1 year ago
Ella Wolf
Created by Ella Wolf almost 8 years ago
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gcse chemistry Flashcards on Structure and Properties, created by Ella Wolf on 05/15/2013.

Resource summary

Question Answer
why do simple molecules not conduct electricity? the molecules do not have an overall electric charge
why do giant ionic lattices have high melting and boiling points? large amounts of energy are needed to break the many strong bonds
what 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
what is special about shape memory alloys? give an example they can return to their original shape after being deformed eg) Nitinol used in dental braces
what do the properties of polymers depend upon? what they are made from and the conditions under which they were made
why are Low density and High density polythene different? they were produced using different catalysts and reaction conditions
what are plastics that have individual tangled polymer chains? thermosoftening
what are the properties of thermosetting plastics? they consist of polymer chains with crosslinks betwen them so they do not melt when they are heated
why 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
what size of structure does nano science refer to ? structures that are 1-100nanometers
why may nano-particles have different properties to the same materials in bulk? they have a higher surface area to volume ratio
when can ionic compounds conduct electricity and why? when molten or dissolved in water because the ions are free to move and carry the current
in diamond, how many bonds does each carbon atom form, what type of bond? each carbon atom forms 4 covalent bonds in a giant structure
in graphite, each carbon atom bonds to how may others? each carbon atom covalently bonds to three others forming layers
why can graphite conduct heat and electricity? like metals, graphite has delocalised electrons which can carry current
how 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
what can carbon also form with different numbers of carbon atoms? fullerenes
what are the uses of fullerenes? (4) -drug delivery into the body -lubricants -catalysts -in nanotubes for reinforcing materials
why can metals conduct heat and electricity? the delocalised electrons in their structure carry charge and move throughout the material
why can metals be bent and shaped? the layers of atoms in metals are able to slide over one another
Do substances that consist of simple molecules have low or high melting/boiling points? low
do substances that have simple molecules have weak or strong inter molecular forces? weak
incomparision to intermolecular forces, are the covalent bonds strong or weak strong
which forces are overcome when a simple molecular substance melts or boils? the intermolecular forces.. the covalent bonds are still intact
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