Giant Covalent Structures and Fullerenes Flashcards
In giant covalent structures, how strong are the atoms bonded?
All of the atoms are bonded to each other by strong covalent bonds.
What are the melting and boiling points like in giant covalent structures?
They have very high melting and boiling points as lots of energy is needed to break the covalent bonds.
Do giant covalent structures conduct electricity?
Generally giant covalent structures don’t conduct electricity, as they don’t contain charged particles (apart from graphite and graphene).
Are giant covalent structures soluble in water?
No.
What are diamond, graphite and graphene all made up of?
A network of carbon atoms.
In diamond, how many covalent bonds does each carbon atom make?
Each carbon atom makes four covalent bonds.
What melting point does diamond have, and why?
Diamond has a high melting point, because the strong covalent bonds require lots of energy to break.
In diamond, how are the carbon atoms arranged?
The strong covalent bonds hold the atoms in a rigid lattice structure, making diamond really hard.
How is diamond used?
It’s used to strengthen cutting tools because it is really hard.
In graphite, how many covalent bonds does each carbon atom make?
Each carbon atom makes three covalent bonds.
In graphite, how are the carbon atoms arranged?
The covalent bonds create sheets of carbon atoms arranged in hexagons.
Are there covalent bonds between the layers in graphite?
No, they are only held together weakly, so they’re free to move over each other. This makes graphite soft and slippery.
How is graphite used?
It’s ideal as a lubricating material because it’s soft and slippery.
Can also be used to make electrodes as each carbon has a free electron to conduct electricity.
What melting point does graphite have?
Graphite has a high melting point - the covalent bonds in the layers need loads of energy to break.
Can graphite conduct electricity?
Yes.
Why can graphite conduct electricity?
Because only three out of each carbon’s four outer electrons are used in bonds, so each carbon atom has one electron that’s delocalised (free) and can move.
What is graphene?
One layer of graphite - a sheet of carbon atoms joined together in hexagons.
What are fullerenes?
Fullerenes are molecules of carbon, shaped like closed tubes or hollow balls.
What is the usual arrangement of carbon atoms in fullerenes?
Carbon atoms are arranged in hexagons, but can also contain pentagons (rings of five carbons) or heptagons (rings of seven carbons).
How can fullerenes be used?
Fullerenes can be used to ‘cage’ other molecules.
The fullerene structure forms around another atom or molecule, which is then trapped inside.
This could be used to deliver a drug to cells in the body.
Why are fullerenes useful for making industrial catalysts?
Because fullerenes have a huge surface area.
What are industrial catalysts (made of fullerenes)?
Individual catalyst molecules attached to fullerenes (the bigger the surface area the better).
What are nanotubes?
Nanotubes are fullerenes. They are tiny cylinders of graphene.
Can nanotubes conduct electricity?
Yes, because they are made of graphene.
What is the tensile strength of nanotubes?
Nanotubes have a high tensile strength (they don’t break when stretched).
How are nanotubes used?
They are used to strengthen materials without adding much weight, so they can be used to strengthen sports equipment that must be strong and light (e.g. tennis rackets).
