C2.2 Structure And Properties Flashcards
Ionic compounds consist of a giant structure of ions arranged in a ________
The attractive _______ between the ions act in all _________ and are very strong
Lattice
Forces
Directions
It take a lot of ______ to break up a giant ionic lattice.
To separate to ions we have to ______ all the electrostatic forces of attractions
This means that they have ______ melting and boiling points
Force/energy
Break/overcome
High
Describe current flow in a liquid and a solid.
In a liquid form the electrons can move around so the current can flow
In a solid the electrons can’t move around so the current stops
Describe current in molten.
Once ions are molten or dissolved, they are free to move around
Therefore the ions can carry their electrical charge through the molten liquid
The positive ions go to the negative electrode and vice versa.
Define intermolecular
These are forces acting between individual molecules
Define intramolecular
The forces acting in a molecule holding the atoms together
What are intermolecular forces?
Very weak
Are intramolecular forces strong or weak?
Strong covalent bonds
Describe the structure of diamond
Diamond is made of entirely carbon atoms. It’s made when carbon is out under extremely high pressure and temperature.
Diamond has a melting point of 3550 degrees Celsius and is the hardest naturally formed substance known. It’s a covalent bond but is an exception as its a giant structure
Describe the structure of silicon dioxide
Used in production of glass
Has a melting point of 1600 degrees Celsius
Giant structure
High boiling point and melting point
Describe the structure of graphite
Each carbon atom forms 3 covalent bonds. The extra electron that is not used to make a bond exists as a free (delocalised) electron. Just as in metals the delocalised electrons can carry the charge when a current is applied. Graphite exists as separate layers that can slide over each other (this is why it’s used in pencils)
Has a melting point of 3600 degrees c
What are fullerenes?
Made by conjoined hexagonal carbon rings
It’s uses are:
Drug delivery
Inlubricants
Catalysts in reactions
To make nano tubes to reinforce structures
What’s an allotrope?
Each of 2 or more different physical forms in which an element can exist
Eg. Diamond, graphite and charcoal
Define an alloy
A mixture with at least one metal in it
Why can we bend and shape metals?
The layers in an atom can slide past each other so you can bend them because they can move
Why is steel strong?
It’s an alloy of iron and its stronger because there are no layers
Why are alloys strong?
The contain atoms of different sizes which distorts the regular arrangements of atoms. This makes it more difficult for the layers to slide over each other, so alloys are harder than pure metals.
What are smart alloys? Give examples
They remember their original shape so if they’re deformed they can return to their original shape usually by heating it.
Examples are braces, shape memory glasses and shape memory stent to keep a blocked blood vessel open.
Define polymer
A long chain of monomers with double bonds
What affects the properties of a polymer?
Length of chains Type of monomers Side links and branches Temperature Time take for polymer to cool down Other chemicals present
What are some properties of LD polyethene
Low density
Has branches formed at high pressure making them hard to pack together
Give properties of HD polyethene
High density
Formed at lower pressure and using a catalyst at 50 degrees c
Polymer chains are straighter allowing them to pack closer together
What’s a thermosoftening polymer?
The tangled web of polymer chains are relatively easy to separate
When heated molecules unwind and can slide past each other.
The material is flexible when it’s hot and can be shaped
When it cools it hardens
When the polymer is heated the weak intermolecular forces are broken so becomes soft
What’s a thermosetting polymer?
Chains fixed together by strong covalent bonds - cross linking
When the polymer is heated the chains are linked to each other and can’t slide past each other
Once mounded the plastic will not soften and can’t be reshaped
What’s vulcanisation?
A chemical process for converting natural rubber or related polymers into more durable materials from the addition of sulphur. These additives modify the polymer by forming cross links between individual polymer chains
What is one nano metre?
1 billionth of a metre
What is nanoscience?
Science on a very small scale
What are benefits of nanoscience?
You can change one atom at a time in a structure and we will be able to create extremely small machines.
Nano medicine only targets s specific part of the body, you don’t have to travel through the whole body
What are the risks with nanoscience?
Could be used badly for terrorism or spying
Nanoparticles are very reactive so if it gets into food or water it can be dangerous. This is because they have a huge surface area
How big is an atom compared to a nanoparticle?
Smaller
Nanoparticle strange in size from about _____ down to about ____
100nm to 1nm
What are uses of nanoscience
Medicine Machines Brain implants Catalysts because they're very reactive Suntan lotion
What are potential future creations for nanoscience?
It might be used for future diseases and restructuring atoms in our body to fight diseases or prevent tumours. Also it could make all clothing water repellent so nothing could get dirty.
