Giant Covalent Structures : Diamond, Graphite, Graphene + Fullerene Flashcards
(17 cards)
What state are they are room temperature
Solids because they have high melting and boiling points
Why do giant covalent substances all have high melting and boiling points
They have millions of strong covalent bonds that have to be broken to melt or boil these substances.
This takes a great deal of energy.
What element is diamond formed from?
Carbon
Diamond Structure
Carbon - four electrons in the outer shell
Each carbon atom forms covalent bonds with 4 other carbon atoms
Diamond contains a huge number of carbon atoms joined by covalent bonds
Why is diamond an extremely hard substance ?
Diamond contains a huge number of carbon atoms joined by covalent bonds
Why does diamond have a very high melting point ?
We need to break all of the covalent bonds which takes a huge amount of energy.
Why can’t diamond conduct electricity?
All of the outer electrons are in covalent bonds so there are no free electrons to carry a charge
What arrangement is diamond
Tetrahedral
Properties of graphite
Soft and slippery
A very high melting and boiling point
Good conductor of electricity and heat
Structure of graphite
Made from carbon
Each carbon atom forms covalent bonds to 3 other carbon atoms forming hexagonal rings.
They are arranged into layers and there are no covalent bonds between layers.
Why is graphite soft and slippery
The carbon bonds form hexagonal ring which are arranged into layers. There are no covalent bonds between layers so they can slide over each other .
Why does graphite have a high melting and boiling point
It contains a large number of strong covalent bonds. If we want to melt graphite , we have to break those bonds. This takes a great deal of energy.
Why is graphite a good conductor of electricity and heat?
Graphite is formed from carbon . The carbons has 4 electrons in its outer shell, but in graphite it only bonds to 3 other carbon atoms. This means there is a left over electron which are released from the carbon atoms. These are called delocalised electrons.
These delocalised electrons can move meaning they can conduct electricity and thermal energy.
What is graphene?
Graphene is a single layer of graphite.
It is only one atom thick
Why is graphene a good conductor of electricity ?
Has delocalised electrons which can move through the molecule carrying electrical charge.
Will be useful in electrical devices.
Why is graphene strong with a high melting point ?
As large number of strong covalent bonds which require a great deal of energy to break.
Makes it useful for producing new materials.
Structure of fullerenes
Made from carbon
Hollow shapes
Hexagonal rings of carbon atoms
Can also have 5 or 7 rings
